WO2020246220A1 - Radiography system and enlarged absorption contrast image generation method - Google Patents

Radiography system and enlarged absorption contrast image generation method Download PDF

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Publication number
WO2020246220A1
WO2020246220A1 PCT/JP2020/019495 JP2020019495W WO2020246220A1 WO 2020246220 A1 WO2020246220 A1 WO 2020246220A1 JP 2020019495 W JP2020019495 W JP 2020019495W WO 2020246220 A1 WO2020246220 A1 WO 2020246220A1
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Prior art keywords
image
absorption
interest
contrast image
subject
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PCT/JP2020/019495
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French (fr)
Japanese (ja)
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千穂 巻渕
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コニカミノルタ株式会社
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
    • G01N23/02—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material
    • G01N23/04—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material
    • G01N23/041—Phase-contrast imaging, e.g. using grating interferometers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
    • G01N23/02—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material
    • G01N23/04—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material
    • G01N23/046—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material using tomography, e.g. computed tomography [CT]

Definitions

  • the present invention relates to a radiography system and a magnified absorption contrast image generation method.
  • X-ray images used for medical and industrial purposes are images obtained by the absorption contrast method.
  • contrast is formed by attenuating the X-ray intensity when X-rays pass through the subject.
  • a phase contrast method has been proposed in which contrast is obtained by changing the phase of X-rays. For example, phase-contrast imaging is performed to obtain a highly visible X-ray image by edge enhancement using refraction of X-rays during magnified imaging (see, for example, Patent Document 1).
  • the absorption contrast method is effective for shooting subjects with large X-ray absorption such as metal and bone.
  • the phase contrast method is expected to be applied to X-ray image diagnosis because it has a higher sensitivity to substances composed of light elements with low X-ray absorption and soft tissues of the human body than the conventional absorption contrast method. ing.
  • the Talbot effect is a phenomenon in which when the first lattice is irradiated with highly coherent light, the lattice images are formed at regular intervals in the traveling direction of the light. This grid image is called a self-image, and the self-image may be observed directly, but in general, the Talbot interferometer places a second grid at the position where the self-image is connected to convert moire fringes with a larger period. ..
  • a phase contrast image of the subject can be obtained by calculating the phase change of the moire fringes depending on the subject.
  • Non-Patent Document 1 a Talbot-low interferometer has been proposed in which a radiation source grid is installed between the X-ray source and the first grid to enable the use of an X-ray source having low coherence (for example, Non-Patent Document 1). reference).
  • a method of phase-contrast imaging has been proposed by observing the projected image of the absorption type first lattice without using Talbot interference (see, for example, Non-Patent Document 2). Similar to the Talbot interferometer, it is also possible to place the second grid in front of the detector and convert it into moire fringes with a larger period.
  • the moire fringes referred to in the present application include moire fringes in which a self-image due to the Talbot effect is converted by a second grid and moire fringes in which a projection image of an absorption type first grid is converted by a second grid, regardless of the method. It is a periodic pattern generated on the surface of the radiation detector by two or more grids.
  • a plurality of periodic pattern images having different phases can be taken, and three types of reconstructed images, a differential phase image, a small-angle scattered image, and an absorption image, can be created by calculation based on the principle of fringe scanning.
  • the differential phase image is an image of the refraction angle of X-rays. It has excellent depiction of defects such as the shape of subjects composed of light elements, cracks, and voids.
  • the small-angle scattering image is an image of small-angle scattering of X-rays, and can detect an aggregate of minute structures smaller than the pixel size.
  • the absorption image is an image of the absorption of X-rays, and is excellent in depiction of a metal having a large X-ray absorption.
  • a method of creating a differential phase image, a small-angle scattered image, and an absorption image from one fine periodic pattern image of about several pixels by using a Fourier transform method is also known (see, for example, Non-Patent Documents 2 and 3). .. Although the reconstructed image obtained by the Fourier transform method has lower spatial resolution than the fringe scanning method, it does not require a plurality of moire fringe images unlike the fringe scanning method.
  • a fluoroscope or ⁇ CT using a minute X-ray source has a spatial resolution on the order of ⁇ m by photographing at a high magnification, and the minute structure itself can be observed.
  • the field of view becomes smaller in proportion to it.
  • the imaging time of ⁇ CT is long, one imaging takes 10 minutes to several hours, and the output data is three-dimensional volume data, so the data size is very large. That is, although the microstructure itself can be observed, there is a problem that the inspectable range is very narrow.
  • a microstructure or a minute defect position is identified using a Talbot interferometer and the minute structure or defect is observed with a fluoroscope with high spatial resolution or ⁇ CT, precise inspection can be performed in a short time, but a different device is used. Therefore, it is difficult to align the subject, it takes time, and a positioning error is likely to occur. In addition, extremely complicated work such as moving a subject and sharing shooting data is required between different devices.
  • An object of the present invention is to enable one device to efficiently inspect the shape and size of micron-order microstructures, cracks, voids, and the like.
  • a radiation imaging system including a radiation imaging device in which a radiation source, one or more grids, and a radiation detector are provided side by side in the irradiation axis direction.
  • a periodic pattern image of a subject is photographed by the radiation photographing apparatus using the lattice, a phase contrast image, a scattered contrast image, and an absorption contrast generated based on these images and the periodic pattern image based on the periodic pattern image.
  • An image generation means for generating at least one of two or more composite images of an image
  • An area of interest setting means for setting one or a plurality of areas of interest for the subject based on an image generated by the image generation means.
  • An enlarged absorption contrast image generation means for generating an enlarged absorption contrast image in which the area of interest is enlarged by taking an enlarged image of the area of interest set by the area of interest setting means by the radiography apparatus. To be equipped.
  • the invention according to claim 2 is the invention according to claim 1.
  • the phase contrast image is a differential phase image, a phase CT image, and a phase image.
  • the invention according to claim 3 is the invention according to claim 1 or 2.
  • the scattering contrast image is a small-angle scattering image, a small-angle scattering CT image, or a small-angle scattering orientation image.
  • the invention according to claim 4 is the invention according to any one of claims 1 to 3.
  • two or more of the phase contrast image, the scattered contrast image, and the absorption contrast image, or a part of the image are weighted and added, subtracted, divided, or multiplied and superimposed. It is an image or an image that has been overlaid using colors.
  • the invention according to claim 5 is the invention according to any one of claims 1 to 4.
  • the absorption contrast image is an absorption image, a differential absorption image, or an absorption CT image
  • the enlarged absorption contrast image is an absorption image, a differential absorption image, or a differential absorption image taken by enlarging the subject more than the absorption contrast image. It is an absorption CT image.
  • the invention according to claim 6 is the invention according to any one of claims 1 to 5.
  • the magnifying absorption contrast image generation means generates the magnifying absorption contrast image from the periodic pattern image by using a fringe scanning method or a Fourier transform method.
  • the invention according to claim 7 is the invention according to any one of claims 1 to 5.
  • the magnifying absorption contrast image generating means performs magnified imaging of the region of interest while moving the one or a plurality of lattices in the slit periodic direction of the lattice by the radiographing apparatus, or at the time of photographing the periodic pattern image.
  • the magnified image of the region of interest is taken while being moved in the direction of the irradiation axis with respect to the position of, or the region of interest is rotated around the irradiation axis with respect to the time of photographing the periodic pattern image.
  • the magnified image is taken, or the scatterer is placed in the field of view to perform the magnified image of the region of interest to generate the magnified absorption contrast image.
  • the magnifying absorption contrast image generating means retracts at least one of the grids out of the field of view, or uses a detection region in the radiation detector in which a periodic pattern is not formed by the grids to generate a region of interest. A magnified image is taken to generate the magnified absorption contrast image.
  • the invention according to claim 9 is the invention according to any one of claims 1 to 8.
  • the magnifying absorption contrast image generating means increases the distance between the radiation detector and the subject, shortens the distance between the radiation source and the subject, or both in the radiography apparatus. The area of interest is magnified and photographed.
  • the invention according to claim 10 is the invention according to any one of claims 1 to 9.
  • the radiography apparatus is configured to be capable of photographing at a plurality of different focal diameters. At the time of the magnified shooting by the magnifying absorption contrast image generating means, a focus smaller than that at the time of shooting the periodic pattern image by the image generating means is used.
  • the invention according to claim 11 is the invention according to any one of claims 1 to 10.
  • the area of interest setting means sets one or a plurality of areas designated from at least one of the phase contrast image, the scattered contrast image, and the composite image in the subject by user operation.
  • the invention according to claim 12 is the invention according to any one of claims 1 to 10.
  • the region of interest setting means sets one or a plurality of regions of interest by analyzing at least one of the phase contrast image, the scattered contrast image, and the composite image.
  • the invention according to claim 13 is the invention according to any one of claims 1 to 12.
  • the image generated by the image generation means, the position information of the area of interest in the image, and the enlarged absorption contrast image in which the area of interest is enlarged are stored in association with each other.
  • the invention according to claim 14 is the invention according to any one of claims 1 to 13.
  • a setting means for setting one or more magnifications or spatial resolutions is provided.
  • the magnifying and absorbing contrast image generation means divides the region of interest for each region of interest according to the field of view size determined by the magnification or spatial resolution set by the setting means and photographs the region of interest a plurality of times, or within the region of interest. Shoot multiple times with different magnifications centered on one point.
  • a magnifying absorption contrast image generation method comprising a radiographing apparatus in which a radiation source, one or more grids, and a radiation detector are provided side by side in the irradiation axis direction.
  • a periodic pattern image of a subject is photographed by the radiation photographing apparatus using the lattice, a phase contrast image, a scattered contrast image, and an absorption contrast generated based on these images and the periodic pattern image based on the periodic pattern image.
  • An area of interest setting step of setting one or a plurality of areas of interest to the subject based on the image generated in the image generation step.
  • An enlarged absorption image generation step of generating an enlarged absorption contrast image in which the area of interest is enlarged by taking an enlarged image of the area of interest set in the area of interest setting step by the radiography apparatus. including.
  • the present invention is not limited to the illustrated examples.
  • an example in which the present invention is applied to a radiography system using a Talbot interferometer will be described, but the present invention is not limited to the one using a Talbot interferometer, and at least the first lattice is used. It is used to capture a plurality of periodic pattern images based on radiation intensity modulated by the projection of the first lattice or the Talbot effect, and generate a phase contrast image, a scattered contrast image, and an absorption contrast image by calculation based on the periodic pattern image. It can be applied if it is an interferometry system.
  • an example using the radiographing apparatus 1A using a one-dimensional lattice (a blind-shaped lattice having periodicity in only one direction) will be described, but a two-dimensional lattice (periodic in two or more directions) will be described.
  • a lattice having a property may be used.
  • As the first lattice a ⁇ -type phase lattice, a ( ⁇ / 2) type phase lattice, or an absorption lattice may be used, and the type of the diffraction grating does not matter.
  • the phase contrast image is an image based on the phase of the periodic pattern, and examples thereof include a differential phase image, a phase CT image, and a phase image obtained by integrating the differential phase image.
  • the scattering contrast image is an image based on the visibility of a periodic pattern, and examples thereof include a small-angle scattering image, a small-angle scattering CT image, and a plurality of small-angle scattering orientation images obtained from small-angle scattering images taken at a plurality of angles.
  • the absorption contrast image include an absorption image based on the average value of the periodic pattern, a conventional absorption image that does not use the periodic pattern, a differential absorption image obtained by differentiating the absorption image, an absorption CT image, and the like.
  • FIG. 1 is a diagram schematically showing a radiography system 100A according to an embodiment of the present invention.
  • the radiography system 100A includes a radiography apparatus 1A and a controller 5.
  • the radiography apparatus 1A performs X-ray photography with a Talbot interferometer, and the controller 5 uses the moire fringe image obtained by the X-ray photography to reconstruct an image (phase contrast image, scattered contrast image, absorption contrast image), etc. To generate.
  • a radiography system for photographing by using X-rays will be described as an example, but other radiations such as neutron rays and gamma rays may be used.
  • the radiographing apparatus 1A includes a radiation source 11, a collimator / additional filter 112, a subject table 13, a first grid 14, a second grid 15, a radiation detector 16, and a support column. 17 and.
  • the radiation photographing apparatus 1A is a horizontal type, and the radiation source 11, the subject table 13, the first grid 14, the second grid 15, and the radiation detector 16 are arranged in this order in the z direction, which is the irradiation axis direction.
  • the radiation source 11, the collimator / additional filter 112, the subject stand 13, the first grid 14, the second grid 15, and the radiation detector 16 have a moving mechanism 11a, a moving mechanism 112a, a moving / rotating mechanism 13a, 14a, and 15a, respectively. It is attached to the support column 17 via the moving mechanism 16a.
  • the radiation source 11 includes an X-ray tube, and the X-ray tube generates X-rays to irradiate the X-rays in the z direction.
  • the X-ray tube for example, a Coolidge X-ray tube or a rotating anode X-ray tube can be used.
  • the anode tungsten, molybdenum, or the like can be used. It is preferable that the radiation source 11 can be photographed with different focal diameters because the diameters of the plurality of different focal points 111 can be switched, or the radiation sources 11 have a plurality of radiation sources having different focal diameters.
  • the radiation source 11 is configured to be movable in the z direction by the moving mechanism 11a.
  • the moving mechanism 11a may have any configuration as long as the radiation source 11 can be linearly fed in the z direction by driving a motor or the like.
  • the collimator / additional filter 112 limits the irradiation area of the X-rays emitted from the radiation source 11, and removes low-energy components that do not contribute to imaging from the X-rays emitted from the radiation source 11. ..
  • the collimator / additional filter 112 is configured to be movable in the z direction by a moving mechanism 112a. As the moving mechanism 112a, any configuration may be used as long as the collimator / additional filter 112 can be linearly fed in the z direction by driving a motor or the like.
  • the subject stand 13 is a stand on which the subject H is placed.
  • the subject base 13 is configured to be movable in the x-direction, y-direction, and z-direction by the moving / rotating mechanism 13a. Further, the subject base 13 is configured to be rotatable around the y-axis by the moving / rotating mechanism 13a.
  • the movement / rotation mechanism 13a can be linearly fed in the x-direction, y-direction, and z-direction by driving a motor or the like, and any configuration can be used as long as it can rotate around the y-axis. Good.
  • the subject base 13 is provided between the radiation source 11 and the first grid 14, but the subject base 13 is arranged between the first grid 14 and the second grid 15.
  • the subject H may be arranged between the first grid 14 and the second grid 15.
  • the first lattice 14 (G1 lattice) is a diffraction grating, and as shown in FIG. 2, a plurality of slits are arranged at predetermined intervals in the x direction orthogonal to the irradiation axis direction (here, the z direction). There is.
  • the first lattice 14 is formed on a substrate made of a material having a low radiation absorption rate such as silicon or glass with a material having a large radiation shielding power such as tungsten, lead, or gold, that is, a material having a high radiation absorption rate.
  • the resist layer is masked in a slit shape by photolithography, and UV is irradiated to transfer the slit pattern to the resist layer.
  • a slit structure having the same shape as the pattern is obtained by exposure, and metal is embedded between the slit structures by an electroforming method to form a first lattice 14.
  • the silicon substrate may be deep-drilled with fine fine wires by the so-called ICP method to form a lattice structure using only silicon.
  • the slit period (lattice period) of the first lattice 14 is 1 to 20 ( ⁇ m).
  • the distance between adjacent slits is one cycle.
  • the width of the slit (the length of each slit in the slit cycle direction (x direction)) is 20 to 70 (%) of the slit cycle, preferably 35 to 60 (%).
  • the height of the slit (height in the z direction) is 1 to 100 ( ⁇ m).
  • the first lattice 14 is configured to be movable in the x-direction, y-direction, and z-direction by the moving / rotating mechanism 14a. Further, the first lattice 14 is configured to be rotatable around the irradiation axis by the moving / rotating mechanism 14a. As the moving / rotating mechanism 14a, any configuration is used as long as the first lattice 14 can be linearly fed in the x-direction, y-direction, and z-direction by driving a motor or the like and can rotate around the irradiation axis. You may.
  • the second lattice 15 is a diffraction grating provided with a plurality of slits arranged at predetermined intervals in the x direction orthogonal to the z direction, which is the irradiation axis direction.
  • the second grid 15 can also be formed by photolithography.
  • the slit period d 2 of the second grid 15 is 1 to 20 ( ⁇ m).
  • the width of the slit is 30 to 70 (%) of the slit period, preferably 35 to 60 (%).
  • the height of the slit is 1 to 100 ( ⁇ m), preferably 30 to 500 ( ⁇ m).
  • the second grid 15 is configured to be movable in the x-direction, y-direction, and z-direction by the moving / rotating mechanism 15a. Further, the second lattice 15 is configured to be rotatable around the irradiation axis by the moving / rotating mechanism 15a. As the moving / rotating mechanism 15a, any configuration is used as long as the second lattice 15 can be linearly fed in the x-direction, y-direction, and z-direction by driving a motor or the like and can rotate around the irradiation axis. You may.
  • the grids in the present embodiment, the first grid 14 and the second grid 15 are shown as planes, but they may be curved.
  • a conversion element that generates an electric signal according to the irradiated radiation is arranged two-dimensionally, and the electric signal generated by the conversion element is read as an image signal.
  • the pixel size of the radiation detector 16 is 0.1 to 300 ( ⁇ m), more preferably 1 to 200 ( ⁇ m).
  • the radiation detector 16 is preferably positioned so as to abut the second grid 15. This is because the larger the distance between the second grid 15 and the radiation detector 16, the more blurred the moire fringe image obtained by the radiation detector 16.
  • an FPD Fluorescence Detector
  • the FPD has an indirect conversion type in which radiation is converted into an electric signal by a photoelectric conversion element via a scintillator and a direct conversion type in which radiation is directly converted into an electric signal, and either of them may be used.
  • a radiation detector having an intensity modulation effect of the second grid 15 may be used.
  • a slit scintillator detector in which a groove is dug in the scintillator and used as a lattice-shaped scintillator may be used as the radiation detector 16.
  • Reference 1 Simon Rutishauser et al., "Structured scintillator for hard x-ray gradient interferometry", APPLIED PHYSICS LETTERS 98, 171107 (2011). Since the radiation detector 16 having this configuration has both the second grid 15 and the radiation detector 16, it is not necessary to separately provide the second grid 15. That is, the provision of the slit scintillator detector is the same as the provision of the second grid 15 and the radiation detector 16.
  • the radiation detector 16 is configured to be movable in the x-direction, y-direction, and z-direction by the moving mechanism 16a.
  • the moving mechanism 16a may have any configuration as long as the radiation detector 16 can be linearly fed in the x-direction, y-direction, and z-direction by driving a motor or the like.
  • the radiography apparatus 1A has been described as a so-called horizontal type configured to irradiate X-rays in the horizontal direction (z direction), but the present invention is not limited to this, and the subject below the radiation source 11 provided on the upper side is not limited to this. It may be a so-called vertical type, which is configured to irradiate X-rays toward H. Further, it may be configured to irradiate X-rays from the radiation source 11 provided on the lower side toward the subject H above.
  • the controller 5 includes a control unit 51, an operation unit 52, a display unit 53, a communication unit 54, and a storage unit 55.
  • the control unit 51 includes a CPU (Central Processing Unit) and a RAM (Random Access Memory). ) Etc., and the control unit is each part of the radiography apparatus 1A (for example, radiation source 11, collimator / additional filter 12, radiation detector 16, moving mechanisms 11a, 112a, moving / rotating mechanisms 13a to 15a, moving. It is connected to a mechanism 16a, etc.) and controls the operation of each part of the radiography apparatus 1A to perform imaging. Further, the control unit 51 executes various processes in cooperation with the program stored in the storage unit 55. For example, the control unit 51 executes a magnified shooting control process described later to acquire a magnified absorption contrast image in which the set area of interest is magnified.
  • a CPU Central Processing Unit
  • RAM Random Access Memory
  • the operation unit 52 is configured to include a keyboard equipped with cursor keys, character / number input keys, various function keys, and a pointing device such as a mouse, and controls operation signals input by key operations on the keyboard and mouse operations. Output to unit 51.
  • the operation unit 52 is composed of a touch panel laminated on the display unit 53, an operation signal corresponding to the position of a touch operation by a user's finger or the like is output to the control unit 51.
  • the display unit 53 displays the operation screen, the operating status of the radiography apparatus 1A, and the like on the display according to the display control of the control unit 51.
  • the communication unit 54 includes a communication interface and communicates with an external device on the communication network.
  • the storage unit 55 is composed of a non-volatile semiconductor memory, a hard disk, or the like, and stores a program executed by the control unit 51 and data necessary for executing the program. Further, the storage unit 55 stores the moire fringe image obtained by the radiation detector 16, the reconstructed image and the composite image generated based on the moire fringe image, the enlarged absorption contrast image, and the like in association with each other.
  • the first grid 14 forms a periodic pattern
  • the second grid 15 converts the periodic pattern into moire fringes.
  • the phase of the X-rays shifts depending on the subject H, so that the moire fringes on the moire fringe image are disturbed at the edge of the subject H as shown in FIG. ..
  • the disorder of the moire fringes can be detected by processing the moire fringe image, and the subject image can be imaged. This is the principle of the Talbot interferometer.
  • the periodic pattern is not limited to the moire fringes, and the self-image may be directly photographed, or the shadow of the first lattice 14 may be observed without using the Talbot effect.
  • a moire fringe image necessary for generating a reconstructed image of the subject H is photographed by, for example, a fringe scanning method.
  • the fringe scanning generally, any one of the grids (first grid 14, the second grid 15) (referred to as the second grid 15 in this embodiment) or two grids in the slit periodic direction (the second grid 15) is used.
  • M is a positive integer, M> 2 for absorption contrast image, M> 3 for differential phase contrast image and small angle scattered image
  • the controller 5 controls the imaging by the radiography apparatus 1A according to the user operation, and generates a phase contrast image, a scattered contrast image, and an absorption contrast image based on the moire fringe image acquired by the radiography imaging apparatus 1A. To do.
  • FIGS. 5A to 5D show an absorption image, a differential phase image, a small-angle scattered image, and a small-angle scattered image generated based on a moire fringe image obtained by taking a Talbot image of an aluminum die-cast component as a subject H, respectively. It is a figure which shows the composite image obtained by dividing by the absorption image.
  • FIG. 6 is an image (magnification ratio 100 times) of the surface of the aluminum die-cast component shown in FIGS. 5A to 5D captured by a scanning electron microscope.
  • the imaging range of FIGS. 5A to 5D is 14.1 mm in length ⁇ 45.8 mm in width.
  • the regions indicated by arrows A and B in FIG. 6 are voids of about several hundred ⁇ m, and can be detected by a phase contrast image and a composite image based on the phase contrast image.
  • the region indicated by the arrow C in FIG. 6 is a void group on the order of ⁇ m, and can be detected by a scattered contrast image and a composite image based on the scattered contrast image. Although only the surface of the polished subject is shown in this image, the inside of the subject can be imaged with X-rays.
  • the region shown by the dotted line D is a void of about several hundred ⁇ m.
  • the region indicated by the dotted line E in the small-angle scattered image of FIG. 5C and the region indicated by the dotted line F in the composite image of FIG. 5D are void groups on the order of ⁇ m.
  • minute voids of about several hundred ⁇ m or void groups on the order of ⁇ m cannot be detected.
  • the sensitivity of the phase contrast image or the scattered contrast image decreases in proportion to the distance from the first grid 14 to the subject H.
  • the region of interest is set based on at least one of the phase contrast image, the scattered contrast image, and the composite image, and the set region of interest is magnified and photographed to generate a magnified absorption contrast image.
  • the magnified shooting means that the subject H is shot at a higher magnification than that of the periodic pattern shooting to generate a magnified absorption contrast image which is a magnified absorption contrast image.
  • the magnification of the subject H for capturing the enlarged absorption contrast image is twice the magnification of the first grid 14 (the distance from the radiation source 11 to the radiation detector 16 divided by the radiation source 11 to the first grid 14). That is the above, and 10 times or more is preferable.
  • the composite image is an image obtained by synthesizing two or more of a phase contrast image, a scattered contrast image, and an absorption contrast image.
  • FIG. 7 is a flowchart showing a magnified shooting control process executed by the control unit 51 of the controller 5.
  • the magnified shooting control process is executed in collaboration with the program stored in the control unit 51 and the storage unit 55.
  • the flow of the magnified shooting control process will be described with reference to FIG. 7.
  • the control unit 51 controls the necessary mechanism among the moving mechanisms 11a and 112a, the moving / rotating mechanisms 13a to 15a, and the moving mechanism 16a in the radiography apparatus 1A, and focuses the radiation source 11 on the radiation irradiation axis.
  • the 111, the subject H, the first grid 14, the second grid 15, and the radiation detector 16 are arranged so as to be lined up at preset intervals for periodic pattern imaging, and periodic pattern imaging is performed.
  • the moire fringe image which is a pattern image is acquired (step S1).
  • the periodic pattern photographing means that the subject H is arranged in the vicinity of the first grid 14 and the periodic pattern image is photographed in order to generate the phase contrast image and the scattered contrast image.
  • photography for acquiring a moire fringe image is performed by utilizing the above-mentioned Talbot effect.
  • FIG. 8 shows an arrangement example of the radiation source 11 (focus 111), the subject H, the first grid 14, the second grid 15, and the radiation detector 16 in the periodic pattern photographing.
  • the subject H is arranged so as to be in the vicinity of the first grid 14, and the subject H, the first grid 14, and the second grid 15 are arranged so as to be in the field of view. Taken at.
  • step S1 in the radiation photographing apparatus 1A, the subject H is subjected to Talbot photography without being placed on the subject stand 13, a moire fringe image without a subject (referred to as a BG moire fringe image) is acquired, and the subject H is captured.
  • a moire fringe image with a subject is acquired by performing Talbot photography while mounted on the subject stand 13. For example, as described above, while moving the second grid 15 in the x direction by the fringe scanning method, the subject H is not placed on the subject table 13 and the subject H is placed on the subject base 13, and M times of shooting are performed respectively. , M BG moire fringe images and M subject moire fringe images are acquired.
  • the moire fringe image may be acquired by performing Talbot photography while rotating the subject base 13 around the y-axis by the moving / rotating mechanism 13a.
  • Talbot imaging while rotating the subject base 13 around the y-axis to acquire moire fringe images having different subject angles and reconstructing three-dimensional volume data is called Talbot CT imaging.
  • Talbot CT imaging includes full scan (a method of shooting the subject from the entire circumference of 360 degrees), half scan (a method of shooting the subject from about 180 degrees), and offset scan (a method of shifting the area of interest of the subject from the center of rotation). Any of the shooting methods) can be used.
  • the image may be taken by a laminography method or a tomosynthesis method.
  • the focal diameter of the radiation source 11 is configured to be switchable, or when a plurality of radiation sources having different focal diameters are provided, the one having a larger focal diameter than that at the time of magnified imaging described later is used at the time of periodic pattern imaging. It is preferable to take a picture. This is because as the focal diameter increases, the amount of radiation emitted increases and noise decreases.
  • the moire fringe images acquired by periodic pattern imaging are sequentially transmitted from the radiography apparatus 1A.
  • control unit 51 generates at least one of the phase contrast image, the scattered contrast image, and the composite image based on the acquired moire fringe image (step S2).
  • phase contrast image examples include a differential phase image, a phase CT image, and a phase image.
  • phase contrast images can be generated by calculating a periodic pattern image (here, a moire fringe image) by a known method.
  • the differential phase image generates a differential phase image with a subject and a differential phase image without a subject by calculating the phase of the moire fringes for each of the subject moire fringe image and the BG moire fringe image using the principle of fringe scanning. , It can be generated by subtracting the differential phase image without the subject from the generated differential phase image with the subject.
  • phase CT image the differential phase image obtained by processing the moire fringe image obtained by Talbot CT imaging by the same method as the generation of the differential phase image is filtered and back-projected (Reference 2: V. Revol, et al., “Laminate fibre structure characterization of carbon fibre-reinforced polymers by X-ray scatter dark field imaging with a grating interferometer”, NDT & E International 58, 64-71, (2013))
  • a phase CT image can be generated.
  • the phase image can be generated by integrating the differential phase image in the lattice periodic direction. At that time, if necessary, an unwrapping process for eliminating phase wrapping may be performed in advance.
  • the scattering contrast image examples include a small-angle scattering image, a small-angle scattering CT image, a small-angle scattering orientation image, and the like, as described above.
  • These scattered contrast images can be generated by calculating a periodic pattern image (here, a moire fringe image) by a known method.
  • the small-angle scattered CT image can be generated by reconstructing the moire fringe image obtained by Talbot CT imaging by the same method as the generation of the small-angle scattered image.
  • the relative angle between the subject H and the lattice (first lattice 14 and second lattice 15) around the irradiation axis is set to 3 angles or more (for example, 0 °, 45 °, 90 °).
  • the composite image is an image in which two or more of the phase contrast image, the scattered contrast image, and the absorption contrast image, or a part of the image, are weighted and added, subtracted, divided, or multiplied and superimposed, or a color. It is an image which was superposed using.
  • the absorption contrast image includes an absorption image, a differential absorption image obtained by differentiating the absorption image, and an absorption CT image.
  • the absorption image can be generated by X-ray photography without using a conventional general periodic pattern, but can also be generated by using a periodic pattern image.
  • the average value for each corresponding pixel of a plurality of images obtained by shooting the fringe scanning method is calculated to obtain an absorption image with a subject and an absorption image without a subject. It can be generated by generating each of them, dividing the generated absorbed image with a subject and the generated absorbed image without a subject, and then performing logarithmic conversion processing.
  • the average value may be obtained by Fourier transforming one moire fringe image by the Fourier transform method (see, for example, Non-Patent Documents 2 and 3).
  • the moire fringe image may be subjected to a binning process in advance. As a result, although the spatial resolution is lowered, noise can be reduced and graininess can be improved.
  • control unit 51 sets the region of interest based on the image generated in step S2 (step S3).
  • step S3 the control unit 51 displays, for example, the phase contrast image, the scattered contrast image, and / or the composite image generated in step S2 on the display unit 53, and the region of interest is operated by the user's operation unit 52. Accepts the settings of.
  • the control unit 51 may automatically set the region of interest by image analysis.
  • the phase contrast image, the scattered contrast image, and / or the composite image generated in step S2 are binarized, and a high signal region in which the signal value is equal to or higher than a predetermined threshold value is set as the region of interest. This makes it possible to set a defective region such as a crack or a void as a region of interest.
  • a reference image obtained by photographing a product having no problem in advance is stored in the storage unit 55, and the stored reference image and the phase contrast generated in step S2 are stored.
  • a difference image from an image, a scattered contrast image, and / or a composite image may be generated, and a portion having a large difference may be set as a region of interest. Only one area of interest can be set, or a plurality of areas of interest can be set. Further, when setting the region of interest, not only one image but also a plurality of types of images (for example, a small-angle scattered image and a differential phase image) may be used for the setting.
  • the control unit 51 sets the shooting conditions (step S4).
  • a user interface for setting the enlargement ratio or spatial resolution is displayed on the display unit 53, and the enlargement ratio or spatial resolution is set according to the operation of the operation unit 52.
  • the magnification or spatial resolution can be set for each region of interest. Then, the number of divisions of the region of interest, the number of times of shooting, and the shooting position for each shooting are determined and set according to the field of view size determined by the set magnification or the required resolution.
  • magnification spatial resolution
  • the region of interest may be divided and photographed, or the magnification of the region of interest fits within the field of view.
  • the number of shots, and the magnification and shooting position for each shot so that the magnification is changed stepwise around the center to achieve the final set magnification (or spatial resolution). May be decided.
  • an absorption contrast image is also generated in step S2, and the tube voltage is increased when it is determined from the absorption contrast image that the transmittance is low, and the tube voltage is decreased when it is determined that the contrast is low.
  • the optimum irradiation conditions for magnified imaging may be determined and set based on the absorption contrast image, such as increasing the irradiation dose.
  • the control unit 51 performs magnified imaging of the region of interest based on the set imaging conditions to generate an enlarged absorption contrast image in which the region of interest is enlarged (step S5). That is, the radiography imaging device 1A performs magnified imaging for the number of imaging times determined by the magnification ratio set in step S4 and the imaging position.
  • the enlarged absorption contrast image is an enlarged absorption contrast image (enlarged absorption image (enlarged absorption image), enlarged absorption CT image (enlarged absorption CT image), or enlarged differential absorption image (enlarged differential absorption image). ).
  • the moving / rotating mechanism 13a is driven to bring the subject base 13 (that is, the subject H) closer to the radiation source 11.
  • the moving mechanism 11a may be driven to bring the radiation source 11 closer to the subject H.
  • the moving mechanism 16a may be driven to separate the radiation detector 16 from the subject H.
  • the position of the collimator / additional filter 12 shows an example of arranging it between the radiation source 11 and the subject H, it may be arranged between the subject H and the first grid 14.
  • step S5 the distance between the radiation detector 16 and the subject H is longer and / or the distance between the radiation source 11 and the subject H is shorter than that at the time of periodic pattern photographing, depending on the enlargement ratio.
  • the position of the subject H (subject stand 13), the radiation detector 16 or the radiation source 11 in the z direction is changed to perform magnified photography, and a magnified absorption contrast image is generated.
  • the focal diameter of the radiation source 11 is configured to be switchable, or when the radiation source 11 has a plurality of radiation sources having different focal diameters, a focal point having a smaller focal diameter during magnified imaging than during periodic pattern imaging. It is preferable to switch to (small focus). This is because the image is blurred when the focal diameter is large.
  • the second grid 15 is moved in the x direction by the moving / rotating mechanism 15a, and M times of magnified imaging of the region of interest is performed, and the average value of the signal values of the obtained M moire fringe images is obtained.
  • An enlarged absorption image of the region of interest is generated by calculating (the average value of the signal values of the M subject moire fringe images for each pixel ⁇ the average value of the signal values of the M BG moire fringe images).
  • the magnifying absorption CT image may be generated by taking a picture by the fringe scanning method while rotating the subject H, or the magnifying absorption CT image may be differentiated to generate the magnifying differential absorption image.
  • one magnified moiré fringe image taken by the Fourier transform method may be Fourier transformed to obtain an average value to generate an enlarged differential absorption image.
  • An image enlarged absorption CT image, enlarged differential absorption image
  • This is preferable because it simplifies shooting.
  • it is preferable to eliminate or reduce the periodic pattern (moire fringes) by any of the following methods for shooting.
  • At least one of the grids is retracted out of the field of view (in the x direction or the y direction), and an enlarged image of the region of interest is performed in a state where a periodic pattern does not occur to enlarge the image. Generates an absorption contrast image.
  • a magnified image of the region of interest may be performed using a detector region in which a periodic pattern is not formed.
  • a plurality of radiation detectors 16 may be used.
  • the collimator / additional filter 112 is adjusted, or the radiation source 11 is angled so that the lattices (first lattice 14 and second lattice 15) are not in the field of view as shown in FIG.
  • the irradiation range of the line is adjusted, the subject H is moved into the irradiation area by the moving / rotating mechanism 13a, and the radiation detector 16 performs magnified imaging of the area of interest in a state where no periodic pattern is generated to generate a magnified absorption contrast image. You may do it.
  • the radiation source 11 has a plurality of radiation sources having different focal diameters (for example, large focus and small focus)
  • a lattice is arranged in advance in the irradiation region of the large focus as shown in FIG.
  • the grid is not arranged in the irradiation area of the small focus, and at the time of magnified shooting, the subject H is moved to the vicinity of the small focus of the irradiation area of the small focus to irradiate X-rays from the small focus.
  • the radiation detector 16 may perform magnified imaging of the region of interest in a state where the periodic pattern does not occur to generate a magnified absorption contrast image.
  • a magnified absorption contrast image is generated by performing magnified shooting of the region of interest by lowering the sharpness of the periodic pattern from that at the time of periodic pattern shooting by any of the following methods (1) to (4). May be good.
  • (1) As shown in FIG. 13A, during X-ray irradiation and accumulation of the radiation detector 16, one or more of the grids are continuously moved or stepped in the x direction, which is the slit periodic direction of the grids, to perform imaging. ..
  • shooting is performed in a state where one or more of the grids are moved in the z direction from the position at the time of periodic pattern shooting.
  • the scatterer 19 is arranged in the irradiation field for photographing.
  • imaging is performed in a state where one or more of the grids are rotated around the irradiation axis as compared with the time of periodic pattern imaging.
  • the scatterer 19 preferably has strong X-ray scattering and weak absorption.
  • the scatterer 19 is configured to be movable in the x-direction or the y-direction by a moving mechanism, and the control unit 51 controls the moving mechanism during magnified imaging so that the scatterer 19 is inserted into the field of view. You may take a picture.
  • One of the radiation source 11 (collimator / additional filter 112), the subject stand 13, the first grid 14, the second grid 15, and the radiation detector 16 from the position for periodic pattern shooting to the position for magnified shooting.
  • the control unit 51 causes the display unit 53 to display the magnified absorption contrast image obtained by the magnified shooting (step S6).
  • the enlarged absorption contrast image is displayed on the display unit 53 as it is.
  • a plurality of magnified absorption contrast images are generated, they are displayed side by side or switched according to the operation of the operation unit 52. Alternatively, it may be automatically played.
  • the enlarged absorption contrast image may be combined and displayed on the phase contrast image, the scattered contrast image, or the composite image generated in step S2.
  • the absorption contrast image is generated based on the moire fringe image taken in step S1. It is preferable that the absorption contrast image and the enlarged absorption contrast image are aligned and combined. Further, an absorption contrast image is generated based on the moire fringe image taken in step S1, the amount of deviation of the enlarged shooting position is obtained based on the absorption contrast image and the enlarged absorption contrast image, and the enlarged image is taken based on the amount of deviation.
  • the position may be corrected and the magnified shooting may be retaken. Alternatively, the shooting position may be stored in the storage unit 55 as a correction amount of the shooting position, and the shooting position may be corrected based on the correction amount at the next shooting.
  • the enlarged absorption contrast image may be displayed after all the areas of interest have been photographed.
  • step S7 determines whether or not the photographing of all the regions of interest is completed.
  • step S7; NO the control unit 51 returns to step S5.
  • step S7; YES the control unit 51 expands and enlarges the image generated in step S2, the position information of the regions of interest in the images, and the regions of interest.
  • the absorption contrast image is associated with the image and stored in the storage unit 55 (step S8), and the magnified imaging control process is completed.
  • the radiography apparatus 1A captures a periodic pattern image of a subject using the first grid 14 and the second grid 15, and based on the periodic pattern image, a phase contrast image, At least one of a scattered contrast image and a composite image of two or more of these images and an absorption contrast image generated based on the periodic pattern image is generated, and one or one of the subjects is generated based on the generated image.
  • a phase contrast image At least one of a scattered contrast image and a composite image of two or more of these images and an absorption contrast image generated based on the periodic pattern image is generated, and one or one of the subjects is generated based on the generated image.
  • Set multiple areas of interest Then, the set area of interest is magnified and photographed by the radiography apparatus 1A to generate an enlarged absorption contrast image in which the area of interest is enlarged. Therefore, the positions of micron-order microstructures, cracks, voids, etc.
  • the micron-order microstructures contained in the subject can be obtained. It is possible to efficiently grasp and measure the shape and size of a body, a crack, a void, and the like.
  • the position desired by the user can be enlarged and observed. It will be possible.
  • phase contrast image, the scattered contrast image and / or the composite image of the subject, the position information of the region of interest in the image, and the enlarged absorption contrast image in which the region of interest is enlarged are stored in the storage unit 55 in association with each other.
  • a radiography apparatus using a Talbot interferometer in which the second grid 15 is moved with respect to the first grid 14 during imaging by the fringe scanning method has been described as an example, but the first grid 14 is used as an example. It may be configured to move with respect to the second lattice 15.
  • the case where a plurality of periodic pattern images are acquired by the fringe scanning method to generate a phase contrast image, a scattered contrast image, and an absorption contrast image has been described as an example, but one image is taken by photographing.
  • the periodic pattern image of the above may be acquired, and a phase contrast image, a scattered contrast image, and an absorption contrast image may be generated from one periodic pattern image by the Fourier conversion method.
  • a scanning method for example, Reference 4 (Masashi Kageyama et al., X-ray phase-imaging scanner with tiled bent gratings for large-field-of-view nondestructive testing, NDT and E International, 105, 19-24, As described in 2019), the phase contrast image, the scattered contrast image, and the absorption contrast image may be generated by moving the subject H with respect to the device or moving the device with respect to the subject H for shooting.) Good. In that case, the magnified shooting may be similarly performed by the scanning method.
  • the radiation detector 16 when the pixels of the radiation detector 16 are composed of small pixels much smaller than the pixel size of a general radiation detector, the radiation detector 16 produces a self-image generated by the first grid 14. Since it can be captured, it may be configured without the second grid 15. Further, if the Talbot order is changed at the time of periodic pattern photographing and the self-image is enlarged by separating the first grid 14 and the radiation detector 16, the self-image can be obtained even with a general pixel size radiation detector 16. Since it can be captured, the configuration may not have the second grid 15.
  • the Talbot interferometer has been described as an example, but the present invention can also be applied to a Talbot low interferometer provided with a radiation source grid 12 in the vicinity of the radiation source 11.
  • a Talbot low interferometer using a radiation source grid 12 is used during periodic pattern imaging.
  • a moving mechanism for moving the source grid 12 is provided, and when photographing by the fringe scanning method, the source grid 12 is moved with respect to the first grid 14 and the second grid 15. It may be that.
  • the radiation source grid 12 is also moved out of the field of view.
  • the radiation source, the collimator / additional filter, the subject stand, the grid, the moving mechanism and the moving / rotating mechanism of the radiation detector do not need to be provided with all of those shown in FIG. 1, and are necessary for photographing by the radiography system. You only need to have things.
  • control unit 51 of the controller 5 is directly connected to each part of the radiography imaging device 1A, but the radiography apparatus 1A is provided with a control unit for controlling each part, and this radiography apparatus
  • the control unit 51 may control each unit of the radiography apparatus 1A via the control unit and the communication unit on the 1A side.
  • a hard disk, a non-volatile memory of a semiconductor, or the like is used as a computer-readable medium for the program according to the present invention, but the present invention is not limited to this example.
  • a portable recording medium such as a CD-ROM can be applied.
  • a carrier wave is also applied as a medium for providing data of a program according to the present invention via a communication line.
  • the present invention can be used in the inspection of materials and products.
  • Radiation imaging system 1A Radiation imaging device 11 Radiation source 13 Subject stand 14 First grid 15 Second grid 16 Radiation detector 17 Support 111 Focus 112 Collimator / additional filter 19 Scatterer 5 Controller 51 Control unit 52 Operation unit 53 Display unit 54 Communication unit 55 Storage unit

Abstract

According to the present invention, it is possible to efficiently inspect the shape and size of micron-order microstructures, cracks, voids, or the like with a single device.　According to the radiography system, a periodic pattern image of a subject is captured by a radiography device by using a first grid and a second grid, at least one among a phase contrast image, a scattered contrast image, and a composite image of two or more images among the phase contrast image, the scattered contrast image, and an absorption contrast image generated on the basis of the periodic pattern image is generated on the basis of the periodic pattern image, and one or a plurality of areas-of-interest is set on basis of the generated images. Then, the set areas-of-interests are enlarged and image-captured by the radiography device to generate an enlarged absorption contrast image in which the areas-of-interests are enlarged.

Description

放射線撮影システム及び拡大吸収コントラスト画像生成方法Radiation imaging system and magnified absorption contrast image generation method
　本発明は、放射線撮影システム及び拡大吸収コントラスト画像生成方法に関する。 The present invention relates to a radiography system and a magnified absorption contrast image generation method.
　一般的に、医療用、産業用で用いられているＸ線画像のほとんどは、吸収コントラスト法による画像である。吸収コントラスト法は、Ｘ線が被写体を透過したときのＸ線強度の減衰によりコントラストを形成する。一方、Ｘ線の位相変化によってコントラストを得る位相コントラスト法が提案されている。例えば、拡大撮影時のＸ線の屈折を利用したエッジ強調によって視認性の高いＸ線画像を得る位相コントラスト撮影が行われている（例えば、特許文献１参照）。 Generally, most of the X-ray images used for medical and industrial purposes are images obtained by the absorption contrast method. In the absorption contrast method, contrast is formed by attenuating the X-ray intensity when X-rays pass through the subject. On the other hand, a phase contrast method has been proposed in which contrast is obtained by changing the phase of X-rays. For example, phase-contrast imaging is performed to obtain a highly visible X-ray image by edge enhancement using refraction of X-rays during magnified imaging (see, for example, Patent Document 1).
　吸収コントラスト法は、金属や骨等のＸ線吸収が大きい被写体の撮影に有効である。これに対し、位相コントラスト法は、Ｘ線吸収が小さい軽元素で構成される物質や、人体の軟部組織に対する感度が従来の吸収コントラスト法に比べて高く、Ｘ線画像診断への適用が期待されている。 The absorption contrast method is effective for shooting subjects with large X-ray absorption such as metal and bone. On the other hand, the phase contrast method is expected to be applied to X-ray image diagnosis because it has a higher sensitivity to substances composed of light elements with low X-ray absorption and soft tissues of the human body than the conventional absorption contrast method. ing.
　位相コントラスト撮影の１つとして、タルボ効果を利用するタルボ干渉計も検討されている（例えば、特許文献２参照）。タルボ効果とは、第１格子に可干渉性の高い光を照射すると、光の進行方向に一定周期でその格子像を結ぶ現象をいう。この格子像は自己像と呼ばれ、自己像を直接観測しても良いが、一般的にタルボ干渉計は自己像を結ぶ位置に第２格子を配置し、より周期の大きなモアレ縞を変換する。被写体によるモアレ縞の位相変化を演算することで、被写体の位相コントラスト画像を得ることができる。
　また、Ｘ線源と第１格子の間に線源格子を設置し、可干渉性の低いＸ線源の使用を可能としたタルボ・ロー干渉計も提案されている（例えば、非特許文献１参照）。 As one of the phase contrast imaging, a Talbot interferometer utilizing the Talbot effect has also been studied (see, for example, Patent Document 2). The Talbot effect is a phenomenon in which when the first lattice is irradiated with highly coherent light, the lattice images are formed at regular intervals in the traveling direction of the light. This grid image is called a self-image, and the self-image may be observed directly, but in general, the Talbot interferometer places a second grid at the position where the self-image is connected to convert moire fringes with a larger period. .. A phase contrast image of the subject can be obtained by calculating the phase change of the moire fringes depending on the subject.
In addition, a Talbot-low interferometer has been proposed in which a radiation source grid is installed between the X-ray source and the first grid to enable the use of an X-ray source having low coherence (for example, Non-Patent Document 1). reference).
　また、タルボ干渉を用いず、吸収型第１格子の投影像を観測することで、位相コントラスト撮影する方法も提案されている（例えば、非特許文献２参照）。タルボ干渉計同様、第２格子を検出器の前に配置し、より周期の大きなモアレ縞に変換することも可能である。本出願でいうモアレ縞とは、タルボ効果による自己像を第２格子で変換したモアレ縞、および吸収型第１格子の投影像を第２格子で変換したモアレ縞を含み、方法は問わず、二枚以上の格子で放射線検出器面上に発生させた周期パターンである。 Further, a method of phase-contrast imaging has been proposed by observing the projected image of the absorption type first lattice without using Talbot interference (see, for example, Non-Patent Document 2). Similar to the Talbot interferometer, it is also possible to place the second grid in front of the detector and convert it into moire fringes with a larger period. The moire fringes referred to in the present application include moire fringes in which a self-image due to the Talbot effect is converted by a second grid and moire fringes in which a projection image of an absorption type first grid is converted by a second grid, regardless of the method. It is a periodic pattern generated on the surface of the radiation detector by two or more grids.
　位相の異なる周期パターン画像を複数枚撮影し、縞走査の原理に基づく演算により、微分位相画像、小角散乱画像、吸収画像の３種類の再構成画像を作成することができる。微分位相画像は、Ｘ線の屈折角を画像化したものである。軽元素で構成される被写体の形状やクラック、ボイドなどの欠陥の描写性に優れている。小角散乱画像は、Ｘ線の小角散乱を画像化したもので、画素サイズ以下の微小構造の集合体を検出可能である。吸収画像は、Ｘ線の吸収を画像化したもので、Ｘ線吸収が大きい金属などの描写に優れている。
　また、数画素程度の細かい周期パターン画像１枚からフーリエ変換法を用いて、微分位相画像、小角散乱画像、吸収画像を作成する手法も知られている（例えば、非特許文献２、３参照）。フーリエ変換法により得られる再構成画像は縞走査法に比べて空間分解能が落ちるものの、縞走査法のように複数枚のモアレ縞画像を必要としない。 A plurality of periodic pattern images having different phases can be taken, and three types of reconstructed images, a differential phase image, a small-angle scattered image, and an absorption image, can be created by calculation based on the principle of fringe scanning. The differential phase image is an image of the refraction angle of X-rays. It has excellent depiction of defects such as the shape of subjects composed of light elements, cracks, and voids. The small-angle scattering image is an image of small-angle scattering of X-rays, and can detect an aggregate of minute structures smaller than the pixel size. The absorption image is an image of the absorption of X-rays, and is excellent in depiction of a metal having a large X-ray absorption.
Further, a method of creating a differential phase image, a small-angle scattered image, and an absorption image from one fine periodic pattern image of about several pixels by using a Fourier transform method is also known (see, for example, Non-Patent Documents 2 and 3). .. Although the reconstructed image obtained by the Fourier transform method has lower spatial resolution than the fringe scanning method, it does not require a plurality of moire fringe images unlike the fringe scanning method.
特開２００７－２６８０３３号公報JP-A-2007-26803 国際公開第２００４／０５８０７０号パンフレットInternational Publication No. 2004/058070 Pamphlet
　上述のように、微分位相画像では軽元素で構成される被写体の密度変化やクラック、ボイドなどの欠陥を従来の吸収画像よりも明瞭に描写性できる。また小角散乱画像では、画素サイズよりも小さなμｍオーダーの微小構造集合体やクラック等を捉えることができる。しかしながら、被写体を第１格子から離すと感度が低下するため第１格子付近に被写体を配置して撮影する必要があり、微小なＸ線源を用いても被写体拡大率を上げることができないため、十分な空間分解能を得ることができない。つまり微小構造集合体の有無を検出できるが、微小構造の大きさや形状などを測定することはできない。一方で、微小なＸ線源を用いた透視装置やμＣＴは高拡大で撮影することでμｍオーダーの空間分解能を有し、微小構造そのものを観察することができる。しかしながら、十分な空間分解能を得るためには拡大率を上げる必要があり、それに比例して視野は小さくなる。例えば数μｍの空間分解能を得るには、視野は数ｍｍから１０ｍｍ程度となるのが一般的である。またμＣＴの撮影時間は長く、１撮影に１０分～数時間がかかり、出力データは三次元ボリュームデータのためデータサイズが非常に大きい。つまり、微小構造そのものを観察することができるが、検査可能な範囲は非常に狭いという課題がある。タルボ干渉計を用いて微小構造や微小な欠陥位置を特定し、高空間分解能な透視装置やμＣＴで微小構造や欠陥を観察すれば短時間で精密な検査が可能となるが、異なる装置を用いるため、被写体の位置合わせが難しく時間がかかる上にポジショニングエラーが発生しやすい。また異なる装置間で、被写体の移動や撮影データの共有など非常に煩雑な作業が必要である。 As described above, in the differential phase image, defects such as density changes, cracks, and voids of the subject composed of light elements can be described more clearly than in the conventional absorption image. Further, in the small-angle scattered image, it is possible to capture microstructure aggregates and cracks on the order of μm, which are smaller than the pixel size. However, if the subject is separated from the first grid, the sensitivity decreases, so it is necessary to place the subject in the vicinity of the first grid for shooting, and even if a minute X-ray source is used, the subject magnification cannot be increased. Sufficient spatial resolution cannot be obtained. That is, the presence or absence of the microstructure aggregate can be detected, but the size and shape of the microstructure cannot be measured. On the other hand, a fluoroscope or μCT using a minute X-ray source has a spatial resolution on the order of μm by photographing at a high magnification, and the minute structure itself can be observed. However, in order to obtain sufficient spatial resolution, it is necessary to increase the magnification, and the field of view becomes smaller in proportion to it. For example, in order to obtain a spatial resolution of several μm, the field of view is generally about several mm to 10 mm. Further, the imaging time of μCT is long, one imaging takes 10 minutes to several hours, and the output data is three-dimensional volume data, so the data size is very large. That is, although the microstructure itself can be observed, there is a problem that the inspectable range is very narrow. If a microstructure or a minute defect position is identified using a Talbot interferometer and the minute structure or defect is observed with a fluoroscope with high spatial resolution or μCT, precise inspection can be performed in a short time, but a different device is used. Therefore, it is difficult to align the subject, it takes time, and a positioning error is likely to occur. In addition, extremely complicated work such as moving a subject and sharing shooting data is required between different devices.
　本発明の課題は、１台の装置でミクロンオーダーの微小構造体やクラック、ボイド等の形状や大きさを効率的に検査できるようにすることである。 An object of the present invention is to enable one device to efficiently inspect the shape and size of micron-order microstructures, cracks, voids, and the like.
　上記課題を解決するため、請求項１に記載の発明は、
　放射線源と、１又は複数の格子と、放射線検出器と、が放射線照射軸方向に並んで設けられた放射線撮影装置を備える放射線撮影システムであって、
　前記放射線撮影装置により前記格子を用いて被写体の周期パターン画像を撮影し、前記周期パターン画像に基づき、位相コントラスト画像、散乱コントラスト画像、これらの画像と前記周期パターン画像に基づいて生成された吸収コントラスト画像のうち二以上の画像の合成画像、のうち少なくとも一つを生成する画像生成手段と、
　前記画像生成手段により生成された画像に基づいて前記被写体に一又は複数の関心領域を設定する関心領域設定手段と、
　前記関心領域設定手段により設定された関心領域を前記放射線撮影装置により拡大撮影して前記関心領域が拡大された拡大吸収コントラスト画像を生成する拡大吸収コントラスト画像生成手段と、
　を備える。 In order to solve the above problems, the invention according to claim 1 is
A radiation imaging system including a radiation imaging device in which a radiation source, one or more grids, and a radiation detector are provided side by side in the irradiation axis direction.
A periodic pattern image of a subject is photographed by the radiation photographing apparatus using the lattice, a phase contrast image, a scattered contrast image, and an absorption contrast generated based on these images and the periodic pattern image based on the periodic pattern image. An image generation means for generating at least one of two or more composite images of an image,
An area of interest setting means for setting one or a plurality of areas of interest for the subject based on an image generated by the image generation means.
An enlarged absorption contrast image generation means for generating an enlarged absorption contrast image in which the area of interest is enlarged by taking an enlarged image of the area of interest set by the area of interest setting means by the radiography apparatus.
To be equipped.
　請求項２に記載の発明は、請求項１に記載の発明において、
　前記位相コントラスト画像は、微分位相画像、位相ＣＴ画像、位相画像である。 The invention according to claim 2 is the invention according to claim 1.
The phase contrast image is a differential phase image, a phase CT image, and a phase image.
　請求項３に記載の発明は、請求項１又は２に記載の発明において、
　前記散乱コントラスト画像は、小角散乱画像、小角散乱ＣＴ画像、又は小角散乱配向画像である。 The invention according to claim 3 is the invention according to claim 1 or 2.
The scattering contrast image is a small-angle scattering image, a small-angle scattering CT image, or a small-angle scattering orientation image.
　請求項４に記載の発明は、請求項１～３のいずれか一項に記載の発明において、
　前記合成画像は、前記位相コントラスト画像、前記散乱コントラスト画像、前記吸収コントラスト画像のうち二つ以上の画像全体又は画像の一部を重みづけして加算、減算、除算、もしくは乗算して重ね合わせた画像、又は色を用いて重ね合わせ処理した画像である。 The invention according to claim 4 is the invention according to any one of claims 1 to 3.
In the composite image, two or more of the phase contrast image, the scattered contrast image, and the absorption contrast image, or a part of the image, are weighted and added, subtracted, divided, or multiplied and superimposed. It is an image or an image that has been overlaid using colors.
　請求項５に記載の発明は、請求項１～４のいずれか一項に記載の発明において、
　前記吸収コントラスト画像は、吸収画像、微分吸収画像、又は吸収ＣＴ画像であり、前記拡大吸収コントラスト画像は、前記吸収コントラスト画像よりも前記被写体を拡大して撮影された吸収画像、微分吸収画像、又は吸収ＣＴ画像である。 The invention according to claim 5 is the invention according to any one of claims 1 to 4.
The absorption contrast image is an absorption image, a differential absorption image, or an absorption CT image, and the enlarged absorption contrast image is an absorption image, a differential absorption image, or a differential absorption image taken by enlarging the subject more than the absorption contrast image. It is an absorption CT image.
　請求項６に記載の発明は、請求項１～５のいずれか一項に記載の発明において、
　前記拡大吸収コントラスト画像生成手段は、縞走査法またはフーリエ変換法を用いて、前記周期パターン画像から前記拡大吸収コントラスト画像を生成する。 The invention according to claim 6 is the invention according to any one of claims 1 to 5.
The magnifying absorption contrast image generation means generates the magnifying absorption contrast image from the periodic pattern image by using a fringe scanning method or a Fourier transform method.
　請求項７に記載の発明は、請求項１～５のいずれか一項に記載の発明において、
　前記拡大吸収コントラスト画像生成手段は、前記放射線撮影装置により、前記１又は複数の格子を、前記格子のスリット周期方向に移動させながら前記関心領域の拡大撮影を行うか、前記周期パターン画像の撮影時の位置に対して前記放射線照射軸方向に移動させた状態で前記関心領域の拡大撮影を行うか、もしくは前記周期パターン画像の撮影時に対して放射線照射軸周りに回転させた状態で前記関心領域の拡大撮影を行うか、又は、散乱体を視野内に配置して前記関心領域の拡大撮影を行って、前記拡大吸収コントラスト画像を生成する。 The invention according to claim 7 is the invention according to any one of claims 1 to 5.
The magnifying absorption contrast image generating means performs magnified imaging of the region of interest while moving the one or a plurality of lattices in the slit periodic direction of the lattice by the radiographing apparatus, or at the time of photographing the periodic pattern image. The magnified image of the region of interest is taken while being moved in the direction of the irradiation axis with respect to the position of, or the region of interest is rotated around the irradiation axis with respect to the time of photographing the periodic pattern image. The magnified image is taken, or the scatterer is placed in the field of view to perform the magnified image of the region of interest to generate the magnified absorption contrast image.
　請求項８に記載の発明は、請求項１～５のいずれか一項に記載の発明において、
　前記拡大吸収コントラスト画像生成手段は、前記放射線撮影装置において、少なくとも一つの前記格子を視野外に退避させるか又は前記放射線検出器における前記格子による周期パターンが形成されない検出領域を用いて前記関心領域の拡大撮影を行って、前記拡大吸収コントラスト画像を生成する。 The invention according to claim 8 is the invention according to any one of claims 1 to 5.
In the radiography apparatus, the magnifying absorption contrast image generating means retracts at least one of the grids out of the field of view, or uses a detection region in the radiation detector in which a periodic pattern is not formed by the grids to generate a region of interest. A magnified image is taken to generate the magnified absorption contrast image.
　請求項９に記載の発明は、請求項１～８のいずれか一項に記載の発明において、
　前記拡大吸収コントラスト画像生成手段は、前記放射線撮影装置において、前記放射線検出器と前記被写体との間の距離を長くするか、前記放射線源と前記被写体の間の距離を短くするか、又はその両方により、前記関心領域を拡大撮影する。 The invention according to claim 9 is the invention according to any one of claims 1 to 8.
The magnifying absorption contrast image generating means increases the distance between the radiation detector and the subject, shortens the distance between the radiation source and the subject, or both in the radiography apparatus. The area of interest is magnified and photographed.
　請求項１０に記載の発明は、請求項１～９のいずれか一項に記載の発明において、
　前記放射線撮影装置は、異なる複数の焦点径での撮影が可能に構成され、
　前記拡大吸収コントラスト画像生成手段による前記拡大撮影時は、前記画像生成手段による前記周期パターン画像の撮影時よりも小さい焦点を用いる。 The invention according to claim 10 is the invention according to any one of claims 1 to 9.
The radiography apparatus is configured to be capable of photographing at a plurality of different focal diameters.
At the time of the magnified shooting by the magnifying absorption contrast image generating means, a focus smaller than that at the time of shooting the periodic pattern image by the image generating means is used.
　請求項１１に記載の発明は、請求項１～１０のいずれか一項に記載の発明において、
　前記関心領域設定手段は、前記被写体における、ユーザー操作により前記位相コントラスト画像、前記散乱コントラスト画像、前記合成画像の少なくとも一つから指定された一又は複数の領域を前記関心領域に設定する。 The invention according to claim 11 is the invention according to any one of claims 1 to 10.
The area of interest setting means sets one or a plurality of areas designated from at least one of the phase contrast image, the scattered contrast image, and the composite image in the subject by user operation.
　請求項１２に記載の発明は、請求項１～１０のいずれか一項に記載の発明において、
　前記関心領域設定手段は、前記位相コントラスト画像、前記散乱コントラスト画像、前記合成画像の少なくとも一つを解析することにより前記一又は複数の関心領域を設定する。 The invention according to claim 12 is the invention according to any one of claims 1 to 10.
The region of interest setting means sets one or a plurality of regions of interest by analyzing at least one of the phase contrast image, the scattered contrast image, and the composite image.
　請求項１３に記載の発明は、請求項１～１２のいずれか一項に記載の発明において、
　前記画像生成手段により生成された画像と、当該画像における前記関心領域の位置情報と、その関心領域を拡大した拡大吸収コントラスト画像と、を対応付けて記憶する記憶手段を備える。 The invention according to claim 13 is the invention according to any one of claims 1 to 12.
The image generated by the image generation means, the position information of the area of interest in the image, and the enlarged absorption contrast image in which the area of interest is enlarged are stored in association with each other.
　請求項１４に記載の発明は、請求項１～１３のいずれか一項に記載の発明において、
　一又は複数の拡大率又は空間分解能を設定する設定手段を備え、
　前記拡大吸収コントラスト画像生成手段は、前記関心領域ごとに、前記設定手段により設定された拡大率又は空間分解能で決まる視野サイズに応じて前記関心領域を分割し複数回撮影する、または前記関心領域内の一点を中心に拡大率を変化させて複数回撮影する。 The invention according to claim 14 is the invention according to any one of claims 1 to 13.
A setting means for setting one or more magnifications or spatial resolutions is provided.
The magnifying and absorbing contrast image generation means divides the region of interest for each region of interest according to the field of view size determined by the magnification or spatial resolution set by the setting means and photographs the region of interest a plurality of times, or within the region of interest. Shoot multiple times with different magnifications centered on one point.
　請求項１５に記載の発明は、
　放射線源と、１又は複数の格子と、放射線検出器と、が放射線照射軸方向に並んで設けられた放射線撮影装置を備える拡大吸収コントラスト画像生成方法であって、
　前記放射線撮影装置により前記格子を用いて被写体の周期パターン画像を撮影し、前記周期パターン画像に基づき、位相コントラスト画像、散乱コントラスト画像、これらの画像と前記周期パターン画像に基づいて生成された吸収コントラスト画像のうち二以上の画像の合成画像、のうち少なくとも一つを生成する画像生成工程と、
　前記画像生成工程において生成された画像に基づいて前記被写体に一又は複数の関心領域を設定する関心領域設定工程と、
　前記関心領域設定工程において設定された関心領域を前記放射線撮影装置により拡大撮影して前記関心領域が拡大された拡大吸収コントラスト画像を生成する拡大吸収画像生成工程と、
　を含む。 The invention according to claim 15
A magnifying absorption contrast image generation method comprising a radiographing apparatus in which a radiation source, one or more grids, and a radiation detector are provided side by side in the irradiation axis direction.
A periodic pattern image of a subject is photographed by the radiation photographing apparatus using the lattice, a phase contrast image, a scattered contrast image, and an absorption contrast generated based on these images and the periodic pattern image based on the periodic pattern image. An image generation step of generating at least one of two or more composite images of an image,
An area of interest setting step of setting one or a plurality of areas of interest to the subject based on the image generated in the image generation step.
An enlarged absorption image generation step of generating an enlarged absorption contrast image in which the area of interest is enlarged by taking an enlarged image of the area of interest set in the area of interest setting step by the radiography apparatus.
including.
　本発明によれば、１台の装置でミクロンオーダーの微小構造体やクラック、ボイド等の形状や大きさを効率的に検査することが可能となる。 According to the present invention, it is possible to efficiently inspect the shape and size of micron-order microstructures, cracks, voids, etc. with one device.
本実施形態に係る放射線撮影システムの構成例を示す図である。It is a figure which shows the configuration example of the radiography system which concerns on this embodiment. 回折格子の平面図である。It is a top view of a diffraction grating. コントローラーの機能的構成を示すブロック図である。It is a block diagram which shows the functional structure of a controller. タルボ干渉計の原理を説明する図である。It is a figure explaining the principle of a Talbot interferometer. 吸収画像の一例を示す図である。It is a figure which shows an example of the absorption image. 微分位相画像の一例を示す図である。It is a figure which shows an example of the differential phase image. 小角散乱画像の一例を示す図である。It is a figure which shows an example of a small angle scattering image. 小角散乱画像を吸収画像で割った合成画像の一例を示す図である。It is a figure which shows an example of the composite image which divided the small angle scattering image by the absorption image. 図５Ａ～図５Ｄの被写体の表面を研磨し走査型電子顕微鏡で撮影した画像である。5A is an image taken by a scanning electron microscope after polishing the surface of the subject of FIGS. 5A to 5D. 図３の制御部により実行される拡大撮影制御処理のフローチャートである。It is a flowchart of the magnifying photography control process executed by the control unit of FIG. 周期パターン撮影時の放射線源、被写体、第１格子、第２格子、放射線検出器の位置関係の一例を示す図である。It is a figure which shows an example of the positional relationship of a radiation source, a subject, a 1st grid, a 2nd grid, and a radiation detector at the time of periodic pattern photography. 拡大撮影時の放射線源、被写体、第１格子、第２格子、放射線検出器の位置関係の一例を示す図である。It is a figure which shows an example of the positional relationship of a radiation source, a subject, a 1st grid, a 2nd grid, and a radiation detector at the time of magnified photography. 拡大撮影時の放射線源、被写体、第１格子、第２格子、放射線検出器の位置関係の一例を示す図である。It is a figure which shows an example of the positional relationship of a radiation source, a subject, a 1st grid, a 2nd grid, and a radiation detector at the time of magnified photography. 拡大撮影時の放射線源、被写体、第１格子、第２格子、放射線検出器の位置関係の一例を示す図である。It is a figure which shows an example of the positional relationship of a radiation source, a subject, a 1st grid, a 2nd grid, and a radiation detector at the time of magnified photography. 周期パターンが発生しない状態で撮影を行うための放射線源、被写体、第１格子、第２格子、放射線検出器の位置関係の一例を示す図である。It is a figure which shows an example of the positional relationship of a radiation source, a subject, a 1st grid, a 2nd grid, and a radiation detector for taking a picture in a state where a periodic pattern is not generated. 周期パターンが発生しない状態で撮影を行うための放射線源、被写体、第１格子、第２格子、放射線検出器の位置関係の一例を示す図である。It is a figure which shows an example of the positional relationship of a radiation source, a subject, a 1st grid, a 2nd grid, and a radiation detector for taking a picture in a state where a periodic pattern is not generated. 周期パターンが発生しない状態で撮影を行うための放射線源、被写体、第１格子、第２格子、放射線検出器の位置関係の一例を示す図である。It is a figure which shows an example of the positional relationship of a radiation source, a subject, a 1st grid, a 2nd grid, and a radiation detector for taking a picture in a state where a periodic pattern is not generated. 周期パターンが発生しない状態で撮影を行うための放射線源、被写体、第１格子、第２格子、放射線検出器の位置関係の一例を示す図である。It is a figure which shows an example of the positional relationship of a radiation source, a subject, a 1st grid, a 2nd grid, and a radiation detector for taking a picture in a state where a periodic pattern is not generated. 周期パターンが発生しない状態で撮影を行うための放射線源、被写体、第１格子、第２格子、放射線検出器の位置関係の一例を示す図である。It is a figure which shows an example of the positional relationship of a radiation source, a subject, a 1st grid, a 2nd grid, and a radiation detector for taking a picture in a state where a periodic pattern is not generated. モアレ縞の鮮明度を低下させるための放射線源、被写体、第１格子、第２格子、放射線検出器の位置関係の一例を示す図である。It is a figure which shows an example of the positional relationship of a radiation source, a subject, a 1st grid, a 2nd grid, and a radiation detector for reducing the sharpness of a moire fringe. モアレ縞の鮮明度を低下させるための放射線源、被写体、第１格子、第２格子、放射線検出器の位置関係の一例を示す図である。It is a figure which shows an example of the positional relationship of a radiation source, a subject, a 1st grid, a 2nd grid, and a radiation detector for reducing the sharpness of a moire fringe. モアレ縞の鮮明度を低下させるための放射線源、被写体、第１格子、第２格子、放射線検出器の位置関係の一例を示す図である。It is a figure which shows an example of the positional relationship of a radiation source, a subject, a 1st grid, a 2nd grid, and a radiation detector for reducing the sharpness of a moire fringe. モアレ縞の鮮明度を低下させるための放射線源、被写体、第１格子、第２格子、放射線検出器の位置関係の一例を示す図である。It is a figure which shows an example of the positional relationship of a radiation source, a subject, a 1st grid, a 2nd grid, and a radiation detector for reducing the sharpness of a moire fringe. 周期パターンが発生しない状態で撮影を行うための放射線源、線源格子、被写体、第１格子、第２格子、放射線検出器の位置関係の一例を示す図である。It is a figure which shows an example of the positional relationship of a radiation source, a radiation source grid, a subject, a 1st grid, a 2nd grid, and a radiation detector for taking a picture in a state where a periodic pattern is not generated.
　以下、図面を参照して本発明の実施形態について説明する。なお、本発明は、図示例に限定されるものではない。
　本実施形態では、本発明をタルボ干渉計を用いた放射線撮影システムに適用した例について説明するが、本発明は、タルボ干渉計を用いたものに限定されるものではなく、少なくとも第１格子を用いて、第１格子の投影またはタルボ効果によって変調された放射線強度に基づく周期パターン画像を複数枚撮影し、周期パターン画像に基づく計算により、位相コントラスト画像、散乱コントラスト画像、吸収コントラスト画像を生成する放射線撮影システムであれば適用することが可能ある。また、本実施形態においては、一次元格子（一方向にのみ周期性を有するすだれ状の格子）を用いた放射線撮影装置１Ａを用いた例について説明するが、２次元格子（２方向以上に周期性を有する格子）を用いても良い。第１格子は、π型位相格子、（π／２）型位相格子、吸収格子を用いてもよく、回折格子の種類は問わない。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the illustrated examples.
In the present embodiment, an example in which the present invention is applied to a radiography system using a Talbot interferometer will be described, but the present invention is not limited to the one using a Talbot interferometer, and at least the first lattice is used. It is used to capture a plurality of periodic pattern images based on radiation intensity modulated by the projection of the first lattice or the Talbot effect, and generate a phase contrast image, a scattered contrast image, and an absorption contrast image by calculation based on the periodic pattern image. It can be applied if it is an interferometry system. Further, in the present embodiment, an example using the radiographing apparatus 1A using a one-dimensional lattice (a blind-shaped lattice having periodicity in only one direction) will be described, but a two-dimensional lattice (periodic in two or more directions) will be described. A lattice having a property) may be used. As the first lattice, a π-type phase lattice, a (π / 2) type phase lattice, or an absorption lattice may be used, and the type of the diffraction grating does not matter.
　ここで、位相コントラスト画像は、周期パターンの位相に基づく画像であり、微分位相画像、位相ＣＴ画像、微分位相画像を積分した位相画像等が挙げられる。
　散乱コントラスト画像は、周期パターンの鮮明度（Visibility）に基づく画像であり、小角散乱画像、小角散乱ＣＴ画像、複数角度で撮影した小角散乱画像から求めた複数の小角散乱配向画像等が挙げられる。
　吸収コントラスト画像は、周期パターンの平均値に基づく吸収画像または周期パターンを用いない従来の吸収画像、吸収画像を微分した微分吸収画像、吸収ＣＴ画像等が挙げられる。 Here, the phase contrast image is an image based on the phase of the periodic pattern, and examples thereof include a differential phase image, a phase CT image, and a phase image obtained by integrating the differential phase image.
The scattering contrast image is an image based on the visibility of a periodic pattern, and examples thereof include a small-angle scattering image, a small-angle scattering CT image, and a plurality of small-angle scattering orientation images obtained from small-angle scattering images taken at a plurality of angles.
Examples of the absorption contrast image include an absorption image based on the average value of the periodic pattern, a conventional absorption image that does not use the periodic pattern, a differential absorption image obtained by differentiating the absorption image, an absorption CT image, and the like.
（放射線撮影システムの構成）
　図１は、本発明の実施形態に係る放射線撮影システム１００Ａを模式的に示した図である。
　図１に示すように、放射線撮影システム１００Ａは、放射線撮影装置１Ａとコントローラー５を備える。放射線撮影装置１Ａはタルボ干渉計によるＸ線撮影を行い、コントローラー５は当該Ｘ線撮影により得られたモアレ縞画像を用いて、再構成画像（位相コントラスト画像、散乱コントラスト画像、吸収コントラスト画像）等を生成する。なお、以下の説明では、Ｘ線を用いて撮影を行う放射線撮影システムを例にとり説明するが、他の放射線、例えば、中性子線、ガンマ線等を用いてもよい。 (Configuration of radiography system)
FIG. 1 is a diagram schematically showing a radiography system 100A according to an embodiment of the present invention.
As shown in FIG. 1, the radiography system 100A includes a radiography apparatus 1A and a controller 5. The radiography apparatus 1A performs X-ray photography with a Talbot interferometer, and the controller 5 uses the moire fringe image obtained by the X-ray photography to reconstruct an image (phase contrast image, scattered contrast image, absorption contrast image), etc. To generate. In the following description, a radiography system for photographing by using X-rays will be described as an example, but other radiations such as neutron rays and gamma rays may be used.
　放射線撮影装置１Ａは、図１に示すように、放射線源１１と、コリメーター・付加フィルター１１２と、被写体台１３と、第１格子１４と、第２格子１５と、放射線検出器１６と、支柱１７と、を備える。放射線撮影装置１Ａは横型であり、放射線源１１、被写体台１３、第１格子１４、第２格子１５、放射線検出器１６は、この順序に放射線照射軸方向であるｚ方向に配置される。 As shown in FIG. 1, the radiographing apparatus 1A includes a radiation source 11, a collimator / additional filter 112, a subject table 13, a first grid 14, a second grid 15, a radiation detector 16, and a support column. 17 and. The radiation photographing apparatus 1A is a horizontal type, and the radiation source 11, the subject table 13, the first grid 14, the second grid 15, and the radiation detector 16 are arranged in this order in the z direction, which is the irradiation axis direction.
　放射線源１１、コリメーター・付加フィルター１１２、被写体台１３、第１格子１４、第２格子１５、放射線検出器１６は、それぞれ移動機構１１ａ、移動機構１１２ａ、移動・回転機構１３ａ、１４ａ、１５ａ、移動機構１６ａを介して支柱１７に取り付けられている。 The radiation source 11, the collimator / additional filter 112, the subject stand 13, the first grid 14, the second grid 15, and the radiation detector 16 have a moving mechanism 11a, a moving mechanism 112a, a moving / rotating mechanism 13a, 14a, and 15a, respectively. It is attached to the support column 17 via the moving mechanism 16a.
　放射線源１１は、Ｘ線管を備え、当該Ｘ線管によりＸ線を発生させてｚ方向にＸ線を照射する。Ｘ線管としては、例えばクーリッジＸ線管や回転陽極Ｘ線管を用いることができる。陽極としては、タングステンやモリブデンなどを用いることができる。
　放射線源１１は、異なる複数の焦点１１１の径が切り替え可能に構成されているか、又は焦点径の異なる複数の放射線源を有している等により、焦点径を変えて撮影できることが好ましい。 The radiation source 11 includes an X-ray tube, and the X-ray tube generates X-rays to irradiate the X-rays in the z direction. As the X-ray tube, for example, a Coolidge X-ray tube or a rotating anode X-ray tube can be used. As the anode, tungsten, molybdenum, or the like can be used.
It is preferable that the radiation source 11 can be photographed with different focal diameters because the diameters of the plurality of different focal points 111 can be switched, or the radiation sources 11 have a plurality of radiation sources having different focal diameters.
　放射線源１１は、移動機構１１ａによりｚ方向に移動可能に構成されている。移動機構１１ａは、モーター等の駆動により、放射線源１１をｚ方向に直線送り可能であればどのような構成のものを用いてもよい。 The radiation source 11 is configured to be movable in the z direction by the moving mechanism 11a. The moving mechanism 11a may have any configuration as long as the radiation source 11 can be linearly fed in the z direction by driving a motor or the like.
　コリメーター・付加フィルター１１２は、放射線源１１から照射されるＸ線の照射領域を制限するとともに、放射線源１１から照射されるＸ線の中から撮影に寄与しない低エネルギー成分を除去するものである。
　コリメーター・付加フィルター１１２は、移動機構１１２ａによりｚ方向に移動可能に構成されている。移動機構１１２ａは、モーター等の駆動により、コリメーター・付加フィルター１１２をｚ方向に直線送り可能であればどのような構成のものを用いてもよい。 The collimator / additional filter 112 limits the irradiation area of the X-rays emitted from the radiation source 11, and removes low-energy components that do not contribute to imaging from the X-rays emitted from the radiation source 11. ..
The collimator / additional filter 112 is configured to be movable in the z direction by a moving mechanism 112a. As the moving mechanism 112a, any configuration may be used as long as the collimator / additional filter 112 can be linearly fed in the z direction by driving a motor or the like.
　被写体台１３は、被写体Ｈを載置するための台である。被写体台１３は、移動・回転機構１３ａによりｘ方向、ｙ方向、ｚ方向に移動可能に構成されている。また、被写体台１３は、移動・回転機構１３ａによりｙ軸周りに回転可能に構成されている。移動・回転機構１３ａは、モーター等の駆動により、被写体台１３をｘ方向、ｙ方向、ｚ方向に直線送り可能で、ｙ軸周りに回転可能であればどのような構成のものを用いてもよい。
　なお、本実施形態では、放射線源１１と第１格子１４の間に被写体台１３が設けられていることとしているが、被写体台１３を第１格子１４と第２格子１５の間に配置して、被写体Ｈが第１格子１４と第２格子１５の間に配置されるようにしてもよい。 The subject stand 13 is a stand on which the subject H is placed. The subject base 13 is configured to be movable in the x-direction, y-direction, and z-direction by the moving / rotating mechanism 13a. Further, the subject base 13 is configured to be rotatable around the y-axis by the moving / rotating mechanism 13a. The movement / rotation mechanism 13a can be linearly fed in the x-direction, y-direction, and z-direction by driving a motor or the like, and any configuration can be used as long as it can rotate around the y-axis. Good.
In the present embodiment, the subject base 13 is provided between the radiation source 11 and the first grid 14, but the subject base 13 is arranged between the first grid 14 and the second grid 15. The subject H may be arranged between the first grid 14 and the second grid 15.
　第１格子１４（Ｇ１格子）は回折格子であり、図２に示すように、放射線照射軸方向（ここではｚ方向）と直交するｘ方向に複数のスリットが所定間隔で配列されて設けられている。第１格子１４はシリコンやガラスといった放射線の吸収率が低い材質の基板上に、タングステン、鉛、金といった放射線の遮蔽力が大きい、つまり放射線の吸収率が高い材質により形成される。例えば、フォトリソグラフィーによりレジスト層がスリット状にマスクされ、ＵＶが照射されてスリットのパターンがレジスト層に転写される。露光によって当該パターンと同じ形状のスリット構造が得られ、電鋳法によりスリット構造間に金属が埋め込まれて、第１格子１４が形成される。あるいは、いわゆるＩＣＰ法によりシリコン基板に微細細線で深掘加工を行い、シリコンのみで格子構造を形成することとしてもよい。
　第１格子１４のスリット周期（格子周期）は１～２０（μｍ）である。スリット周期は、図２に示すように隣接するスリット間の距離を１周期とする。スリットの幅（各スリットのスリット周期方向（ｘ方向）の長さ）はスリット周期の２０～７０（％）であり、好ましくは３５～６０（％）である。スリットの高さ（ｚ方向の高さ）は１～１００（μｍ）である。 The first lattice 14 (G1 lattice) is a diffraction grating, and as shown in FIG. 2, a plurality of slits are arranged at predetermined intervals in the x direction orthogonal to the irradiation axis direction (here, the z direction). There is. The first lattice 14 is formed on a substrate made of a material having a low radiation absorption rate such as silicon or glass with a material having a large radiation shielding power such as tungsten, lead, or gold, that is, a material having a high radiation absorption rate. For example, the resist layer is masked in a slit shape by photolithography, and UV is irradiated to transfer the slit pattern to the resist layer. A slit structure having the same shape as the pattern is obtained by exposure, and metal is embedded between the slit structures by an electroforming method to form a first lattice 14. Alternatively, the silicon substrate may be deep-drilled with fine fine wires by the so-called ICP method to form a lattice structure using only silicon.
The slit period (lattice period) of the first lattice 14 is 1 to 20 (μm). As the slit cycle, as shown in FIG. 2, the distance between adjacent slits is one cycle. The width of the slit (the length of each slit in the slit cycle direction (x direction)) is 20 to 70 (%) of the slit cycle, preferably 35 to 60 (%). The height of the slit (height in the z direction) is 1 to 100 (μm).
　第１格子１４は、移動・回転機構１４ａによりｘ方向、ｙ方向、ｚ方向に移動可能に構成されている。また、第１格子１４は、移動・回転機構１４ａにより放射線照射軸周りに回転可能に構成されている。移動・回転機構１４ａは、モーター等の駆動により、第１格子１４をｘ方向、ｙ方向、ｚ方向に直線送り可能で、放射線照射軸周りに回転可能であればどのような構成のものを用いてもよい。 The first lattice 14 is configured to be movable in the x-direction, y-direction, and z-direction by the moving / rotating mechanism 14a. Further, the first lattice 14 is configured to be rotatable around the irradiation axis by the moving / rotating mechanism 14a. As the moving / rotating mechanism 14a, any configuration is used as long as the first lattice 14 can be linearly fed in the x-direction, y-direction, and z-direction by driving a motor or the like and can rotate around the irradiation axis. You may.
　第２格子１５（Ｇ２格子）は、第１格子１４と同様に、放射線照射軸方向であるｚ方向と直交するｘ方向に複数のスリットが所定間隔で配列されて設けられた回折格子である。第２格子１５もフォトリソグラフィーにより形成することができる。第２格子１５のスリット周期ｄ2は１～２０（μｍ）である。スリットの幅はスリット周期の３０～７０（％）であり、好ましくは３５～６０（％）である。スリットの高さは１～１００（μｍ）であり、好ましくは３０～５００（μｍ）である。 Similar to the first lattice 14, the second lattice 15 (G2 lattice) is a diffraction grating provided with a plurality of slits arranged at predetermined intervals in the x direction orthogonal to the z direction, which is the irradiation axis direction. The second grid 15 can also be formed by photolithography. The slit period d 2 of the second grid 15 is 1 to 20 (μm). The width of the slit is 30 to 70 (%) of the slit period, preferably 35 to 60 (%). The height of the slit is 1 to 100 (μm), preferably 30 to 500 (μm).
　第２格子１５は、移動・回転機構１５ａによりｘ方向、ｙ方向、ｚ方向に移動可能に構成されている。また、第２格子１５は、移動・回転機構１５ａにより放射線照射軸周りに回転可能に構成されている。移動・回転機構１５ａは、モーター等の駆動により、第２格子１５をｘ方向、ｙ方向、ｚ方向に直線送り可能で、放射線照射軸周りに回転可能であればどのような構成のものを用いてもよい。 The second grid 15 is configured to be movable in the x-direction, y-direction, and z-direction by the moving / rotating mechanism 15a. Further, the second lattice 15 is configured to be rotatable around the irradiation axis by the moving / rotating mechanism 15a. As the moving / rotating mechanism 15a, any configuration is used as long as the second lattice 15 can be linearly fed in the x-direction, y-direction, and z-direction by driving a motor or the like and can rotate around the irradiation axis. You may.
　なお、本実施形態において、格子（本実施形態では、第１格子１４及び第２格子１５）は平面として図示しているが、湾曲しているものであってもよい。 In the present embodiment, the grids (in the present embodiment, the first grid 14 and the second grid 15) are shown as planes, but they may be curved.
　放射線検出器１６は、照射された放射線に応じて電気信号を生成する変換素子が２次元状に配置され、当該変換素子により生成された電気信号を画像信号として読み取る。放射線検出器１６の画素サイズは０．１～３００（μｍ）であり、さらに好ましくは１～２００（μｍ）である。放射線検出器１６は第２格子１５に当接するように位置することが好ましい。第２格子１５と放射線検出器１６間の距離が大きくなるほど、放射線検出器１６により得られるモアレ縞画像がボケるからである。 In the radiation detector 16, a conversion element that generates an electric signal according to the irradiated radiation is arranged two-dimensionally, and the electric signal generated by the conversion element is read as an image signal. The pixel size of the radiation detector 16 is 0.1 to 300 (μm), more preferably 1 to 200 (μm). The radiation detector 16 is preferably positioned so as to abut the second grid 15. This is because the larger the distance between the second grid 15 and the radiation detector 16, the more blurred the moire fringe image obtained by the radiation detector 16.
　放射線検出器１６としては、ＦＰＤ（Flat Panel Detector）、またはフォトンカウンティングディテクターを用いることができる。ＦＰＤには、放射線をシンチレーターを介して光電変換素子により電気信号に変換する間接変換型、放射線を直接的に電気信号に変換する直接変換型があるが、何れを用いてもよい。
　また、放射線検出器１６としては、第２格子１５の強度変調効果を与えた放射線検出器を使用しても良い。例えば、シンチレーターに第２格子１５のスリットと同等の周期および幅で不感領域を与えるために、シンチレーターに溝を掘り、格子状のシンチレーターとしたスリットシンチレーター検出器を放射線検出器１６として用いても良い（参照文献１：Simon Rutishauser et al.,「Structured scintillator for hard x-ray grating interferometry」，APPLIED PHYSICS LETTERS 98, 171107 (2011)）。この構成の放射線検出
器１６は、第２格子１５と放射線検出器１６とを兼ね備えたものであるため、第２格子１５を別途設ける必要はない。即ち、スリットシンチレーター検出器を備えることは、第２格子１５と放射線検出器１６を備えていることと同じである。 As the radiation detector 16, an FPD (Flat Panel Detector) or a photon counting detector can be used. The FPD has an indirect conversion type in which radiation is converted into an electric signal by a photoelectric conversion element via a scintillator and a direct conversion type in which radiation is directly converted into an electric signal, and either of them may be used.
Further, as the radiation detector 16, a radiation detector having an intensity modulation effect of the second grid 15 may be used. For example, in order to give the scintillator a dead region with the same period and width as the slit of the second lattice 15, a slit scintillator detector in which a groove is dug in the scintillator and used as a lattice-shaped scintillator may be used as the radiation detector 16. (Reference 1: Simon Rutishauser et al., "Structured scintillator for hard x-ray gradient interferometry", APPLIED PHYSICS LETTERS 98, 171107 (2011)). Since the radiation detector 16 having this configuration has both the second grid 15 and the radiation detector 16, it is not necessary to separately provide the second grid 15. That is, the provision of the slit scintillator detector is the same as the provision of the second grid 15 and the radiation detector 16.
　放射線検出器１６は、移動機構１６ａによりｘ方向、ｙ方向、ｚ方向に移動可能に構成されている。移動機構１６ａは、モーター等の駆動により、放射線検出器１６をｘ方向、ｙ方向、ｚ方向に直線送り可能であればどのような構成のものを用いてもよい。 The radiation detector 16 is configured to be movable in the x-direction, y-direction, and z-direction by the moving mechanism 16a. The moving mechanism 16a may have any configuration as long as the radiation detector 16 can be linearly fed in the x-direction, y-direction, and z-direction by driving a motor or the like.
　なお、放射線撮影装置１Ａは、Ｘ線を水平方向（ｚ方向）に照射するように構成された、いわゆる横型として説明したが、これに限らず、上側に設けられた放射線源１１から下方の被写体Ｈに向けてＸ線を照射するように構成されている、いわゆる縦型としてもよい。また、下側に設けられた放射線源１１から上方の被写体Ｈに向けてＸ線を照射するように構成してもよい。 The radiography apparatus 1A has been described as a so-called horizontal type configured to irradiate X-rays in the horizontal direction (z direction), but the present invention is not limited to this, and the subject below the radiation source 11 provided on the upper side is not limited to this. It may be a so-called vertical type, which is configured to irradiate X-rays toward H. Further, it may be configured to irradiate X-rays from the radiation source 11 provided on the lower side toward the subject H above.
　コントローラー５は、図３に示すように、制御部５１、操作部５２、表示部５３、通信部５４、記憶部５５を備えて構成されている。 As shown in FIG. 3, the controller 5 includes a control unit 51, an operation unit 52, a display unit 53, a communication unit 54, and a storage unit 55.
　制御部５１は、ＣＰＵ（Central Processing Unit）やＲＡＭ（Random Access Memory
）等から構成され、制御部は、放射線撮影装置１Ａの各部（例えば、放射線源１１、コリメーター・付加フィルター１２、放射線検出器１６、移動機構１１ａ、１１２ａ、移動・回転機構１３ａ～１５ａ、移動機構１６ａ等）に接続されており、放射線撮影装置１Ａの各部の動作を制御して撮影を行う。また、制御部５１は、記憶部５５に記憶されているプログラムとの協働により、各種処理を実行する。例えば、制御部５１は、後述する拡大撮影制御処理を実行し、設定された関心領域を拡大した拡大吸収コントラスト画像を取得する。 The control unit 51 includes a CPU (Central Processing Unit) and a RAM (Random Access Memory).
) Etc., and the control unit is each part of the radiography apparatus 1A (for example, radiation source 11, collimator / additional filter 12, radiation detector 16, moving mechanisms 11a, 112a, moving / rotating mechanisms 13a to 15a, moving. It is connected to a mechanism 16a, etc.) and controls the operation of each part of the radiography apparatus 1A to perform imaging. Further, the control unit 51 executes various processes in cooperation with the program stored in the storage unit 55. For example, the control unit 51 executes a magnified shooting control process described later to acquire a magnified absorption contrast image in which the set area of interest is magnified.
　操作部５２は、カーソルキー、文字・数字入力キー及び各種機能キー等を備えたキーボードと、マウス等のポインティングデバイスを備えて構成され、キーボードに対するキー操作やマウス操作により入力された操作信号を制御部５１に出力する。また、操作部５２が、表示部５３に積層されたタッチパネルにより構成される場合には、ユーザーの指等によるタッチ操作の位置に応じた操作信号を制御部５１に出力する。 The operation unit 52 is configured to include a keyboard equipped with cursor keys, character / number input keys, various function keys, and a pointing device such as a mouse, and controls operation signals input by key operations on the keyboard and mouse operations. Output to unit 51. When the operation unit 52 is composed of a touch panel laminated on the display unit 53, an operation signal corresponding to the position of a touch operation by a user's finger or the like is output to the control unit 51.
　表示部５３は、制御部５１の表示制御に従って、ディスプレイに操作画面、放射線撮影装置１Ａの動作状況等を表示する。 The display unit 53 displays the operation screen, the operating status of the radiography apparatus 1A, and the like on the display according to the display control of the control unit 51.
　通信部５４は通信インターフェイスを備え、通信ネットワーク上の外部機器と通信する。
　記憶部５５は、不揮発性の半導体メモリーやハードディスク等により構成され、制御部５１により実行されるプログラム、プログラムの実行に必要なデータを記憶している。また、記憶部５５は放射線検出器１６によって得られたモアレ縞画像、モアレ縞画像に基づいて生成された再構成画像や合成画像、拡大吸収コントラスト画像等を対応付けて記憶する。 The communication unit 54 includes a communication interface and communicates with an external device on the communication network.
The storage unit 55 is composed of a non-volatile semiconductor memory, a hard disk, or the like, and stores a program executed by the control unit 51 and data necessary for executing the program. Further, the storage unit 55 stores the moire fringe image obtained by the radiation detector 16, the reconstructed image and the composite image generated based on the moire fringe image, the enlarged absorption contrast image, and the like in association with each other.
（放射線撮影システムの動作）
　ここで、上記放射線撮影装置１Ａのタルボ干渉計による撮影方法を説明する。
　図４に示すように、放射線源１１から照射されたＸ線が第１格子１４を透過すると、透過したＸ線がｚ方向に一定の間隔で像を結ぶ。この像を自己像といい、自己像が形成される現象をタルボ効果という。自己像を結ぶ位置に第２格子１５が自己像と概ね平行に配置され、第２格子１５を透過したＸ線によりモアレ縞画像（図４においてＭｏで示す）が得られる。即ち、第１格子１４は、周期パターンを形成し、第２格子１５は周期パターンをモアレ縞に変換する。放射線源１１と第１格子１４間に被写体Ｈが存在すると、被写体ＨによってＸ線の位相がずれるため、図４に示すようにモアレ縞画像上のモアレ縞は被写体Ｈの辺縁を境界に乱れる。このモアレ縞の乱れを、モアレ縞画像を処理することによって検出し、被写体像を画像化することができる。これがタルボ干渉計の原理である。なお、上記周期パターンはモアレ縞だけに限定されず、自己像を直接撮影しても良いし、タルボ効果を用いずに第１格子１４の影を観測しても良い。 (Operation of radiography system)
Here, an imaging method using the Talbot interferometer of the radiography apparatus 1A will be described.
As shown in FIG. 4, when the X-rays emitted from the radiation source 11 pass through the first lattice 14, the transmitted X-rays form an image at regular intervals in the z direction. This image is called a self-image, and the phenomenon in which a self-image is formed is called the Talbot effect. The second grid 15 is arranged substantially parallel to the self-image at the position where the self-image is formed, and a moire fringe image (indicated by Mo in FIG. 4) is obtained by X-rays transmitted through the second grid 15. That is, the first grid 14 forms a periodic pattern, and the second grid 15 converts the periodic pattern into moire fringes. When the subject H exists between the radiation source 11 and the first lattice 14, the phase of the X-rays shifts depending on the subject H, so that the moire fringes on the moire fringe image are disturbed at the edge of the subject H as shown in FIG. .. The disorder of the moire fringes can be detected by processing the moire fringe image, and the subject image can be imaged. This is the principle of the Talbot interferometer. The periodic pattern is not limited to the moire fringes, and the self-image may be directly photographed, or the shadow of the first lattice 14 may be observed without using the Talbot effect.
　放射線撮影装置１Ａにおいては、被写体Ｈの再構成画像を生成するために必要なモアレ縞画像を、例えば、縞走査法により撮影する。縞走査とは、一般的には、格子（第１格子１４、第２格子１５）のうちのいずれか１枚（本実施形態では、第２格子１５とする）または２枚をスリット周期方向（ｘ方向）に相対的に動かしてＭ回（Ｍは正の整数、吸収コントラスト画像はＭ＞２、微分位相コントラスト画像と小角散乱画像はＭ＞３）の撮影（Ｍステップの撮影）を行い、再構成画像を生成するのに必要なＭ枚のモアレ縞画像を取得することをいう。具体的には、移動させる格子のスリット周期をｄ（μｍ）とすると、ｄ／Ｍ（μｍ）ずつ格子をスリット周期方向に動かして撮影を行うことを繰り返し、Ｍ枚のモアレ縞画像を取得する。
　コントローラー５においては、ユーザー操作に応じて、放射線撮影装置１Ａによる撮影を制御したり、放射線撮影装置１Ａにより取得されたモアレ縞画像に基づいて、位相コントラスト画像、散乱コントラスト画像、吸収コントラスト画像を生成したりする。 In the radiography apparatus 1A, a moire fringe image necessary for generating a reconstructed image of the subject H is photographed by, for example, a fringe scanning method. In the fringe scanning, generally, any one of the grids (first grid 14, the second grid 15) (referred to as the second grid 15 in this embodiment) or two grids in the slit periodic direction (the second grid 15) is used. Taken M times (M is a positive integer, M> 2 for absorption contrast image, M> 3 for differential phase contrast image and small angle scattered image) by moving relatively in the x direction (M step shooting). Acquiring M moire fringe images required to generate a reconstructed image. Specifically, assuming that the slit period of the grid to be moved is d (μm), the grid is repeatedly moved in the slit cycle direction by d / M (μm) to perform imaging, and M moire fringe images are acquired. ..
The controller 5 controls the imaging by the radiography apparatus 1A according to the user operation, and generates a phase contrast image, a scattered contrast image, and an absorption contrast image based on the moire fringe image acquired by the radiography imaging apparatus 1A. To do.
　ここで、図５Ａ～図５Ｄは、それぞれアルミダイキャスト部品を被写体Ｈとしてタルボ撮影することにより得られたモアレ縞画像に基づいて生成された吸収画像、微分位相画像、小角散乱画像、小角散乱画像を吸収画像で割り算することにより得られた合成画像、を示す図である。図６は、図５Ａ～図５Ｄに示すアルミダイキャスト部品の表面を走査型電子顕微鏡で捉えた画像（拡大率１００倍）である。図５Ａ～図５Ｄの撮影範囲は、縦１４．１ｍｍ×横４５．８ｍｍである。 Here, FIGS. 5A to 5D show an absorption image, a differential phase image, a small-angle scattered image, and a small-angle scattered image generated based on a moire fringe image obtained by taking a Talbot image of an aluminum die-cast component as a subject H, respectively. It is a figure which shows the composite image obtained by dividing by the absorption image. FIG. 6 is an image (magnification ratio 100 times) of the surface of the aluminum die-cast component shown in FIGS. 5A to 5D captured by a scanning electron microscope. The imaging range of FIGS. 5A to 5D is 14.1 mm in length × 45.8 mm in width.
　図６において矢印Ａ、Ｂで示す領域は、数百μｍ程度のボイドであり、位相コントラスト画像及び位相コントラスト画像に基づく合成画像で検出することができる。図６において矢印Ｃで示す領域は、μｍオーダーのボイド群であり、散乱コントラスト画像及び散乱コントラスト画像に基づく合成画像で検出することができる。この画像では研磨した被写体の表面のみが写っているが、Ｘ線では、被写体内部を画像化できる。 The regions indicated by arrows A and B in FIG. 6 are voids of about several hundred μm, and can be detected by a phase contrast image and a composite image based on the phase contrast image. The region indicated by the arrow C in FIG. 6 is a void group on the order of μm, and can be detected by a scattered contrast image and a composite image based on the scattered contrast image. Although only the surface of the polished subject is shown in this image, the inside of the subject can be imaged with X-rays.
　図５Ｂの微分位相画像において点線Ｄで示す領域は、数百μｍ程度のボイドである。図５Ｃの小角散乱画像において点線Ｅで示す領域及び図５Ｄの合成画像において点線Ｆで示す領域は、μｍオーダーのボイド群である。これに対し、吸収コントラスト画像では、図５Ａに示すように、微小な数百μｍ程度のボイドやμｍオーダーのボイド群は検出することはできない。
　一方、位相コントラスト画像や散乱コントラスト画像は、被写体Ｈを第１格子１４から離して拡大撮影すると、第１格子１４から被写体Ｈの距離に比例して感度が低下する。μＦｏｃｕｓＸ線源を用いて、μｍオーダーの空間分解能を得るためには、被写体ＨをＸ線源直後に配置する必要があるが、そのような高拡大率では、位相コントラスト画像や散乱コントラスト画像の信号値は大幅に低下するため、位相コントラスト画像や散乱コントラスト画像の拡大撮影では、ボイド等の微小構造個別の形状や大きさを測定することができない。これに対し、吸収コントラスト画像は、拡大撮影を行っても信号の強度はほとんど変わらないため、拡大撮影により数百μｍ程度のボイドやμｍオーダーのボイド群を拡大して、その個別の形状や大きさを測定することができる。 In the differential phase image of FIG. 5B, the region shown by the dotted line D is a void of about several hundred μm. The region indicated by the dotted line E in the small-angle scattered image of FIG. 5C and the region indicated by the dotted line F in the composite image of FIG. 5D are void groups on the order of μm. On the other hand, in the absorption contrast image, as shown in FIG. 5A, minute voids of about several hundred μm or void groups on the order of μm cannot be detected.
On the other hand, when the subject H is separated from the first grid 14 and magnified, the sensitivity of the phase contrast image or the scattered contrast image decreases in proportion to the distance from the first grid 14 to the subject H. In order to obtain spatial resolution on the order of μm using the μFocus X-ray source, it is necessary to place the subject H immediately after the X-ray source, but at such a high magnification, the signals of the phase contrast image and the scattered contrast image Since the value drops significantly, it is not possible to measure the shape and size of individual microstructures such as voids in magnified imaging of a phase contrast image or a scattered contrast image. On the other hand, in the absorption contrast image, the signal intensity does not change even if the magnified image is taken, so the voids of about several hundred μm or the void group on the order of μm are enlarged by the magnified image, and their individual shapes and sizes are enlarged. Can be measured.
　そこで、拡大撮影制御処理では、位相コントラスト画像、散乱コントラスト画像、合成画像の少なくとも一つに基づいて、関心領域を設定し、設定された関心領域を拡大撮影して拡大吸収コントラスト画像を生成する。拡大撮影とは、周期パターン撮影時より被写体Ｈの拡大率を高くして撮影を行い、拡大された吸収コントラスト画像である拡大吸収コントラスト画像を生成することをいう。拡大吸収コントラスト画像を撮影する被写体Ｈの拡大率は、第１格子１４の拡大率（放射線源１１から放射線検出器１６までの距離を放射線源１１から第１格子１４で割ったもの）の２倍以上であり、１０倍以上が好ましい。また、合成画像は、位相コントラスト画像、散乱コントラスト画像、吸収コントラスト画像のうち二つ以上を合成した画像である。 Therefore, in the magnified shooting control process, the region of interest is set based on at least one of the phase contrast image, the scattered contrast image, and the composite image, and the set region of interest is magnified and photographed to generate a magnified absorption contrast image. The magnified shooting means that the subject H is shot at a higher magnification than that of the periodic pattern shooting to generate a magnified absorption contrast image which is a magnified absorption contrast image. The magnification of the subject H for capturing the enlarged absorption contrast image is twice the magnification of the first grid 14 (the distance from the radiation source 11 to the radiation detector 16 divided by the radiation source 11 to the first grid 14). That is the above, and 10 times or more is preferable. The composite image is an image obtained by synthesizing two or more of a phase contrast image, a scattered contrast image, and an absorption contrast image.
　図７は、コントローラー５の制御部５１により実行される拡大撮影制御処理を示すフローチャートである。拡大撮影制御処理は、制御部５１と記憶部５５に記憶されているプログラムとの協働により実行される。以下、図７を参照して拡大撮影制御処理の流れについて説明する。 FIG. 7 is a flowchart showing a magnified shooting control process executed by the control unit 51 of the controller 5. The magnified shooting control process is executed in collaboration with the program stored in the control unit 51 and the storage unit 55. Hereinafter, the flow of the magnified shooting control process will be described with reference to FIG. 7.
　まず、制御部５１は、放射線撮影装置１Ａにおいて、移動機構１１ａ、１１２ａ、移動・回転機構１３ａ～１５ａ、移動機構１６ａのうち必要な機構を制御して、放射線照射軸上に放射線源１１の焦点１１１、被写体Ｈ、第１格子１４、第２格子１５、放射線検出器１６が、予め設定された周期パターン撮影用の間隔で並んだ状態となるように配置して周期パターン撮影を行わせ、周期パターン画像であるモアレ縞画像を取得させる（ステップＳ１）。
　ここで、周期パターン撮影とは、位相コントラスト画像、散乱コントラスト画像を生成するため、被写体Ｈを第１格子１４付近に配置して周期パターン画像を撮影することをいう。本実施形態において、周期パターン撮影では、上述のタルボ効果を利用してモアレ縞画像を取得する撮影（タルボ撮影）を行う。 First, the control unit 51 controls the necessary mechanism among the moving mechanisms 11a and 112a, the moving / rotating mechanisms 13a to 15a, and the moving mechanism 16a in the radiography apparatus 1A, and focuses the radiation source 11 on the radiation irradiation axis. The 111, the subject H, the first grid 14, the second grid 15, and the radiation detector 16 are arranged so as to be lined up at preset intervals for periodic pattern imaging, and periodic pattern imaging is performed. The moire fringe image which is a pattern image is acquired (step S1).
Here, the periodic pattern photographing means that the subject H is arranged in the vicinity of the first grid 14 and the periodic pattern image is photographed in order to generate the phase contrast image and the scattered contrast image. In the present embodiment, in the periodic pattern photography, photography for acquiring a moire fringe image (Talbot photography) is performed by utilizing the above-mentioned Talbot effect.
　図８に、周期パターン撮影における放射線源１１（焦点１１１）、被写体Ｈ、第１格子１４、第２格子１５、放射線検出器１６の配置例を示す。周期パターン撮影では、図８に示すように、被写体Ｈが第１格子１４の近傍となるように、また、被写体Ｈ、第１格子１４、第２格子１５が視野内に入るように並んだ状態で撮影される。 FIG. 8 shows an arrangement example of the radiation source 11 (focus 111), the subject H, the first grid 14, the second grid 15, and the radiation detector 16 in the periodic pattern photographing. In the periodic pattern photography, as shown in FIG. 8, the subject H is arranged so as to be in the vicinity of the first grid 14, and the subject H, the first grid 14, and the second grid 15 are arranged so as to be in the field of view. Taken at.
　ステップＳ１では、放射線撮影装置１Ａにおいて、被写体Ｈを被写体台１３に載置しない状態でタルボ撮影を行って、被写体無しのモアレ縞画像（ＢＧモアレ縞画像と呼ぶ）を取得するとともに、被写体Ｈを被写体台１３に載置した状態でタルボ撮影を行って、被写体ありのモアレ縞画像（被写体モアレ縞画像）を取得する。例えば、上述のように、縞走査法により第２格子１５をｘ方向に動かしながら、被写体台１３に被写体Ｈを載置しない状態と被写体Ｈを載置した状態で、それぞれＭ回の撮影を行い、Ｍ枚のＢＧモアレ縞画像及びＭ枚の被写体モアレ縞画像を取得する。
　あるいは、移動・回転機構１３ａにより被写体台１３をｙ軸周りに回転させながらタルボ撮影を行って、モアレ縞画像を取得することとしてもよい。このように、被写体台１３をｙ軸周りに回転させながらタルボ撮影を行って、被写体角度の異なるモアレ縞画像を取得し、三次元のボリュームデータを再構成することをタルボＣＴ撮影と呼ぶ。タルボＣＴ撮影は、フルスキャン（被写体を３６０度全周方向から撮影する方法）、ハーフスキャン（被写体を約１８０度方向から撮影する方法）、オフセットスキャン（被写体の関心領域を回転中心からずらして視野を広げる撮影方法）の何れでも良い。またラミノグラフィー方式、トモシンセシス方式で撮影しても良い。 In step S1, in the radiation photographing apparatus 1A, the subject H is subjected to Talbot photography without being placed on the subject stand 13, a moire fringe image without a subject (referred to as a BG moire fringe image) is acquired, and the subject H is captured. A moire fringe image with a subject (subject moire fringe image) is acquired by performing Talbot photography while mounted on the subject stand 13. For example, as described above, while moving the second grid 15 in the x direction by the fringe scanning method, the subject H is not placed on the subject table 13 and the subject H is placed on the subject base 13, and M times of shooting are performed respectively. , M BG moire fringe images and M subject moire fringe images are acquired.
Alternatively, the moire fringe image may be acquired by performing Talbot photography while rotating the subject base 13 around the y-axis by the moving / rotating mechanism 13a. Such Talbot imaging while rotating the subject base 13 around the y-axis to acquire moire fringe images having different subject angles and reconstructing three-dimensional volume data is called Talbot CT imaging. Talbot CT imaging includes full scan (a method of shooting the subject from the entire circumference of 360 degrees), half scan (a method of shooting the subject from about 180 degrees), and offset scan (a method of shifting the area of interest of the subject from the center of rotation). Any of the shooting methods) can be used. Further, the image may be taken by a laminography method or a tomosynthesis method.
　放射線源１１の焦点径が切り替え可能に構成されている場合、または焦点径の異なる複数の放射線源を備えている場合、周期パターン撮影時には、後述する拡大撮影時よりも焦点径の大きいものを用いて撮影を行うことが好ましい。焦点径が大きくなると照射される放射線量が多くなり、ノイズが減るからである。
　周期パターン撮影により取得されたモアレ縞画像は、放射線撮影装置１Ａから順次送信される。 When the focal diameter of the radiation source 11 is configured to be switchable, or when a plurality of radiation sources having different focal diameters are provided, the one having a larger focal diameter than that at the time of magnified imaging described later is used at the time of periodic pattern imaging. It is preferable to take a picture. This is because as the focal diameter increases, the amount of radiation emitted increases and noise decreases.
The moire fringe images acquired by periodic pattern imaging are sequentially transmitted from the radiography apparatus 1A.
　次いで、制御部５１は、取得したモアレ縞画像に基づいて、位相コントラスト画像、散乱コントラスト画像、合成画像の少なくとも一つを生成させる（ステップＳ２）。 Next, the control unit 51 generates at least one of the phase contrast image, the scattered contrast image, and the composite image based on the acquired moire fringe image (step S2).
　上述のように、位相コントラスト画像としては、微分位相画像、位相ＣＴ画像、位相画像が挙げられる。これらの位相コントラスト画像は、周期パターン画像（ここではモアレ縞画像）を公知の手法により演算することで生成することができる。
　微分位相画像は、被写体モアレ縞画像とＢＧモアレ縞画像のそれぞれについて縞走査の原理を用いてモアレ縞の位相を計算することにより被写体有りの微分位相画像と被写体無しの微分位相画像をそれぞれ生成し、生成した被写体有りの微分位相画像から被写体無しの微分位相画像を減算することにより生成することができる。
　位相ＣＴ画像は、タルボＣＴ撮影によって得られたモアレ縞画像を微分位相画像の生成と同様の手法により処理することにより得られる微分位相画像をフィルター処理し逆投影（参照文献２：V. Revol, et al., “Laminate fibre structure characterization of carbon fibre-reinforced polymers by X-ray scatter dark field imaging with a grating interferometer”, NDT&E International 58, 64-71, (2013)参照）することで三次元データである位相ＣＴ画像を生成することができる。
　位相画像は、微分位相画像を格子周期方向に積分することにより生成することができる。その際、必要に応じて事前に位相の折り返しを無くすアンラップ処理を施しても良い。 As described above, examples of the phase contrast image include a differential phase image, a phase CT image, and a phase image. These phase contrast images can be generated by calculating a periodic pattern image (here, a moire fringe image) by a known method.
The differential phase image generates a differential phase image with a subject and a differential phase image without a subject by calculating the phase of the moire fringes for each of the subject moire fringe image and the BG moire fringe image using the principle of fringe scanning. , It can be generated by subtracting the differential phase image without the subject from the generated differential phase image with the subject.
For the phase CT image, the differential phase image obtained by processing the moire fringe image obtained by Talbot CT imaging by the same method as the generation of the differential phase image is filtered and back-projected (Reference 2: V. Revol, et al., “Laminate fibre structure characterization of carbon fibre-reinforced polymers by X-ray scatter dark field imaging with a grating interferometer”, NDT & E International 58, 64-71, (2013)) A phase CT image can be generated.
The phase image can be generated by integrating the differential phase image in the lattice periodic direction. At that time, if necessary, an unwrapping process for eliminating phase wrapping may be performed in advance.
　散乱コントラスト画像としては、上述のように、小角散乱画像、小角散乱ＣＴ画像、小角散乱配向画像等が挙げられる。これらの散乱コントラスト画像は、周期パターン画像（ここではモアレ縞画像）を公知の手法により演算することで生成することができる。
　小角散乱画像は、被写体モアレ縞画像とＢＧモアレ縞画像のそれぞれについて縞走査の原理を用いてモアレ縞の鮮明度（Visibility）を計算することにより（Visibility＝振幅÷平均値）、被写体有りの小角散乱画像と被写体無しの小角散乱画像をそれぞれ生成し、生成した被写体有りの小角散乱画像を被写体無しの小角散乱画像で割り算した後、対数変換処理することにより生成することができる。
　小角散乱ＣＴ画像は、タルボＣＴ撮影によって得られたモアレ縞画像を小角散乱画像の生成と同様の手法により再構成することにより生成することができる。
　小角散乱配向画像は、被写体Ｈと格子（第１格子１４及び第２格子１５）との放射線照射軸周りの相対角度を３角度以上（例えば、０°、４５°、９０°）に設定して撮影したモアレ縞画像に基づいて生成した複数の小角散乱画像を解析することにより得られる、被写体Ｈ内部の繊維等の物質の配向を表した画像である（例えば、参照文献３：T. H. Jensen, Phys. Rev. B 82, 214103 (2010)参照）。 Examples of the scattering contrast image include a small-angle scattering image, a small-angle scattering CT image, a small-angle scattering orientation image, and the like, as described above. These scattered contrast images can be generated by calculating a periodic pattern image (here, a moire fringe image) by a known method.
The small-angle scattered image is a small-angle image with a subject by calculating the visibility of the moire fringes (Visibility = amplitude ÷ average value) for each of the subject moire fringe image and the BG moire fringe image using the principle of fringe scanning. It can be generated by generating a scattered image and a small-angle scattered image without a subject, respectively, dividing the generated small-angle scattered image with a subject by the small-angle scattered image without a subject, and then performing a logarithmic conversion process.
The small-angle scattered CT image can be generated by reconstructing the moire fringe image obtained by Talbot CT imaging by the same method as the generation of the small-angle scattered image.
In the small-angle scattering orientation image, the relative angle between the subject H and the lattice (first lattice 14 and second lattice 15) around the irradiation axis is set to 3 angles or more (for example, 0 °, 45 °, 90 °). It is an image showing the orientation of a substance such as a fiber inside the subject H, which is obtained by analyzing a plurality of small-angle scattered images generated based on the captured moire fringe image (for example, Reference 3: TH Jensen, Phys). . Rev. B 82, 214103 (2010)).
　合成画像は、位相コントラスト画像、散乱コントラスト画像、吸収コントラスト画像のうち二つ以上の画像全体又は画像の一部を重みづけして加算、減算、除算、もしくは乗算して重ね合わせた画像、又は色を用いて重ね合わせ処理した画像である。 The composite image is an image in which two or more of the phase contrast image, the scattered contrast image, and the absorption contrast image, or a part of the image, are weighted and added, subtracted, divided, or multiplied and superimposed, or a color. It is an image which was superposed using.
　吸収コントラスト画像は、上述のように、吸収画像、吸収画像を微分した微分吸収画像、吸収ＣＴ画像が挙げられる。吸収画像は、従来の一般的な周期パターンを用いないＸ線撮影によって生成することができるが、周期パターン画像を用いても生成することができる。例えば、被写体モアレ縞画像とＢＧモアレ縞画像のそれぞれについて縞走査法の撮影で得られた複数の画像の対応する画素ごとの平均値を算出して被写体有りの吸収画像と被写体無しの吸収画像をそれぞれ生成し、生成した被写体有りの吸収画像と被写体無しの吸収画像を割り算した後、対数変換処理することにより生成することができる。また、フーリエ変換法で１枚のモアレ縞画像をフーリエ変換して平均値を求めても良い（例えば、非特許文献２、３参照）。 As described above, the absorption contrast image includes an absorption image, a differential absorption image obtained by differentiating the absorption image, and an absorption CT image. The absorption image can be generated by X-ray photography without using a conventional general periodic pattern, but can also be generated by using a periodic pattern image. For example, for each of the subject moire fringe image and the BG moire fringe image, the average value for each corresponding pixel of a plurality of images obtained by shooting the fringe scanning method is calculated to obtain an absorption image with a subject and an absorption image without a subject. It can be generated by generating each of them, dividing the generated absorbed image with a subject and the generated absorbed image without a subject, and then performing logarithmic conversion processing. Further, the average value may be obtained by Fourier transforming one moire fringe image by the Fourier transform method (see, for example, Non-Patent Documents 2 and 3).
　なお、ステップＳ２の処理の前に、モアレ縞画像に予めビニング処理を施しても良い。これにより、空間分解能は低下するがノイズを低減させて粒状性を向上させることができる。 Before the process of step S2, the moire fringe image may be subjected to a binning process in advance. As a result, although the spatial resolution is lowered, noise can be reduced and graininess can be improved.
　次いで、制御部５１は、ステップＳ２で生成された画像に基づいて関心領域を設定する（ステップＳ３）。 Next, the control unit 51 sets the region of interest based on the image generated in step S2 (step S3).
　ステップＳ３において、制御部５１は、例えば、ステップＳ２で生成された位相コントラスト画像、散乱コントラスト画像、及び／又は合成画像を表示部５３に表示して、ユーザーの操作部５２の操作により、関心領域の設定を受け付ける。
　または、制御部５１は、画像解析により自動的に関心領域を設定してもよい。例えば、ステップＳ２で生成された位相コントラスト画像、散乱コントラスト画像、及び／又は合成画像を２値化し、信号値が予め定められた閾値以上の高信号領域を関心領域に設定する。これにより、クラックやボイド等の欠陥のある領域を関心領域に設定することができる。または、例えば、被写体Ｈが検査対象の製品等である場合、予め問題のない製品を撮影した基準画像を記憶部５５に記憶しておき、記憶された基準画像とステップＳ２で生成された位相コントラスト画像、散乱コントラスト画像、及び／又は合成画像との差分画像を生成し、差分の大きかった箇所を関心領域に設定してもよい。
　関心領域は、一つのみ設定することもできるし、複数を設定することもできる。また、関心領域の設定時には、一つの画像だけでなく複数種類の画像（例えば、小角散乱画像と微分位相画像）を用いて設定を行ってもよい。 In step S3, the control unit 51 displays, for example, the phase contrast image, the scattered contrast image, and / or the composite image generated in step S2 on the display unit 53, and the region of interest is operated by the user's operation unit 52. Accepts the settings of.
Alternatively, the control unit 51 may automatically set the region of interest by image analysis. For example, the phase contrast image, the scattered contrast image, and / or the composite image generated in step S2 are binarized, and a high signal region in which the signal value is equal to or higher than a predetermined threshold value is set as the region of interest. This makes it possible to set a defective region such as a crack or a void as a region of interest. Alternatively, for example, when the subject H is a product to be inspected, a reference image obtained by photographing a product having no problem in advance is stored in the storage unit 55, and the stored reference image and the phase contrast generated in step S2 are stored. A difference image from an image, a scattered contrast image, and / or a composite image may be generated, and a portion having a large difference may be set as a region of interest.
Only one area of interest can be set, or a plurality of areas of interest can be set. Further, when setting the region of interest, not only one image but also a plurality of types of images (for example, a small-angle scattered image and a differential phase image) may be used for the setting.
　次いで、制御部５１は、撮影条件を設定する（ステップＳ４）。
　例えば、表示部５３に拡大率又は空間分解能を設定するためのユーザーインターフェースを表示し、操作部５２の操作に応じて拡大率又は空間分解能を設定する。複数の関心領域が設定されている場合は、関心領域ごとに拡大率又は空間分解能を設定可能とすることが好ましい。そして、設定された拡大率又は要求分解能で決まる視野サイズに応じた関心領域の分割数、撮影回数及び撮影ごとの撮影位置を決定して設定する。なお、拡大率（空間分解能）が大きく、拡大すると関心領域が視野内に収まらない場合、関心領域を分割して撮影してもよいし、関心領域が視野内に収まる拡大率から、関心領域の中心を中心として段階的に拡大率を変化させて最終的に設定された拡大率（又は空間分解能）となるように撮影が行われるように、撮影回数、及び各撮影ごとの拡大率や撮影位置を決定することとしてもよい。
　また、例えば、ステップＳ２において併せて吸収コントラスト画像を生成しておき、吸収コントラスト画像から透過率が低いと判断した場合には管電圧を上げる、コントラストが小さいと判断した場合には管電圧を下げ、照射線量を上げる等、吸収コントラスト画像に基づいて、拡大撮影時の最適な放射線照射条件を決定して設定してもよい。 Next, the control unit 51 sets the shooting conditions (step S4).
For example, a user interface for setting the enlargement ratio or spatial resolution is displayed on the display unit 53, and the enlargement ratio or spatial resolution is set according to the operation of the operation unit 52. When a plurality of regions of interest are set, it is preferable that the magnification or spatial resolution can be set for each region of interest. Then, the number of divisions of the region of interest, the number of times of shooting, and the shooting position for each shooting are determined and set according to the field of view size determined by the set magnification or the required resolution. If the magnification (spatial resolution) is large and the region of interest does not fit in the field of view when enlarged, the region of interest may be divided and photographed, or the magnification of the region of interest fits within the field of view. The number of shots, and the magnification and shooting position for each shot so that the magnification is changed stepwise around the center to achieve the final set magnification (or spatial resolution). May be decided.
Further, for example, an absorption contrast image is also generated in step S2, and the tube voltage is increased when it is determined from the absorption contrast image that the transmittance is low, and the tube voltage is decreased when it is determined that the contrast is low. , The optimum irradiation conditions for magnified imaging may be determined and set based on the absorption contrast image, such as increasing the irradiation dose.
　次いで、制御部５１は、設定した撮影条件に基づいて、関心領域の拡大撮影を行って、関心領域が拡大された拡大吸収コントラスト画像を生成する（ステップＳ５）。
　すなわち、放射線撮影装置１Ａにより、ステップＳ４で設定した拡大率、撮影位置で決定された撮影回数分、拡大撮影を行う。
　拡大吸収コントラスト画像は、拡大された吸収コントラスト画像（拡大された吸収画像（拡大吸収画像）、拡大された吸収ＣＴ画像（拡大吸収ＣＴ画像）、又は拡大された微分吸収画像（拡大微分吸収画像））である。 Next, the control unit 51 performs magnified imaging of the region of interest based on the set imaging conditions to generate an enlarged absorption contrast image in which the region of interest is enlarged (step S5).
That is, the radiography imaging device 1A performs magnified imaging for the number of imaging times determined by the magnification ratio set in step S4 and the imaging position.
The enlarged absorption contrast image is an enlarged absorption contrast image (enlarged absorption image (enlarged absorption image), enlarged absorption CT image (enlarged absorption CT image), or enlarged differential absorption image (enlarged differential absorption image). ).
　拡大撮影を行うには、放射線源１１、被写体Ｈ、放射線検出器１６の距離関係を周期パターン撮影時から変更する必要がある。具体的には、放射線検出器１６と被写体Ｈ間の距離を長くする、または放射線源１１と被写体Ｈ間の距離を短くする、またはその両方により、関心領域を拡大して撮影することができる。
　例えば、図９Ａに示すように、移動・回転機構１３ａを駆動して被写体台１３を（すなわち、被写体Ｈを）放射線源１１に近づける。または、図９Ｂに示すように、移動機構１１ａを駆動して放射線源１１を被写体Ｈに近づけることとしてもよい。または、図９Ｃに示すように、移動機構１６ａを駆動して放射線検出器１６を被写体Ｈから離すこととしてもよい。なお、コリメーター・付加フィルター１２の位置は、放射線源１１と被写体Ｈの間に配置した例を示しているが、被写体Ｈと第１格子１４の間に配置することとしてもよい。 In order to perform magnified imaging, it is necessary to change the distance relationship between the radiation source 11, the subject H, and the radiation detector 16 from the time of periodic pattern imaging. Specifically, the area of interest can be enlarged and photographed by increasing the distance between the radiation detector 16 and the subject H, shortening the distance between the radiation source 11 and the subject H, or both.
For example, as shown in FIG. 9A, the moving / rotating mechanism 13a is driven to bring the subject base 13 (that is, the subject H) closer to the radiation source 11. Alternatively, as shown in FIG. 9B, the moving mechanism 11a may be driven to bring the radiation source 11 closer to the subject H. Alternatively, as shown in FIG. 9C, the moving mechanism 16a may be driven to separate the radiation detector 16 from the subject H. Although the position of the collimator / additional filter 12 shows an example of arranging it between the radiation source 11 and the subject H, it may be arranged between the subject H and the first grid 14.
　ステップＳ５においては、拡大率に応じて、周期パターン撮影時より放射線検出器１６と被写体Ｈ間の距離が長くなるように、及び／又は放射線源１１と被写体Ｈ間の距離が短くなるように、被写体Ｈ（被写体台１３）、放射線検出器１６又は放射線源１１のｚ方向の位置を変更して拡大撮影を行い、拡大吸収コントラスト画像を生成する。放射線源１１の焦点径が切り替え可能に構成されている場合、又は放射線源１１が焦点径の異なる複数の放射線源を有している場合、拡大撮影時には周期パターン撮影時よりも焦点径の小さい焦点（小焦点）に切り替えることが好ましい。焦点径が大きいと画像がボケるからである。 In step S5, the distance between the radiation detector 16 and the subject H is longer and / or the distance between the radiation source 11 and the subject H is shorter than that at the time of periodic pattern photographing, depending on the enlargement ratio. The position of the subject H (subject stand 13), the radiation detector 16 or the radiation source 11 in the z direction is changed to perform magnified photography, and a magnified absorption contrast image is generated. When the focal diameter of the radiation source 11 is configured to be switchable, or when the radiation source 11 has a plurality of radiation sources having different focal diameters, a focal point having a smaller focal diameter during magnified imaging than during periodic pattern imaging. It is preferable to switch to (small focus). This is because the image is blurred when the focal diameter is large.
　例えば、縞走査法により、移動・回転機構１５ａにより第２格子１５をｘ方向に移動させながらＭ回の関心領域の拡大撮影を行い、得られたＭ枚のモアレ縞画像の信号値の平均値（画素ごとの、Ｍ枚の被写体モアレ縞画像の信号値の平均値÷Ｍ枚のＢＧモアレ縞画像の信号値の平均値）を算出することにより関心領域の拡大吸収画像を生成する。このとき、被写体Ｈを回転させながら縞走査法による撮影を行って拡大吸収ＣＴ画像を生成してもよいし、拡大吸収画像を微分して拡大微分吸収画像を生成してもよい。
　また、フーリエ変換法で１枚の拡大撮影されたモアレ縞画像をフーリエ変換して平均値を求めて拡大微分吸収画像を生成してもよい。 For example, by the fringe scanning method, the second grid 15 is moved in the x direction by the moving / rotating mechanism 15a, and M times of magnified imaging of the region of interest is performed, and the average value of the signal values of the obtained M moire fringe images is obtained. An enlarged absorption image of the region of interest is generated by calculating (the average value of the signal values of the M subject moire fringe images for each pixel ÷ the average value of the signal values of the M BG moire fringe images). At this time, the magnifying absorption CT image may be generated by taking a picture by the fringe scanning method while rotating the subject H, or the magnifying absorption CT image may be differentiated to generate the magnifying differential absorption image.
Further, one magnified moiré fringe image taken by the Fourier transform method may be Fourier transformed to obtain an average value to generate an enlarged differential absorption image.
　縞走査法を用いずに、すなわち、格子送りごとの撮影を必要とせず、画像再構成も必要とせずに１回の拡大撮影（ＣＴでは角度ごとに１回の拡大撮影）を行って拡大吸収画像（拡大吸収ＣＴ画像、拡大微分吸収画像）を生成してもよい。これにより、撮影が簡易となるので好ましい。この場合、以下のいずれかの手法で周期パターン（モアレ縞）を消去または低減させて撮影を行うことが好ましい。 Magnification absorption by performing one magnified image (one magnified image for each angle in CT) without using the fringe scanning method, that is, without the need for imaging for each grid feed and without the need for image reconstruction. An image (enlarged absorption CT image, enlarged differential absorption image) may be generated. This is preferable because it simplifies shooting. In this case, it is preferable to eliminate or reduce the periodic pattern (moire fringes) by any of the following methods for shooting.
　例えば、図１０Ａ～図１０Ｃに示すように、格子の少なくとも一つを視野外に（ｘ方向又はｙ方向に）退避させて、周期パターンが発生しない状態で関心領域の拡大撮影を行って、拡大吸収コントラスト画像を生成する。なお、図１０Ｃに示すように、第１格子１４及び第２格子１５の双方を退避させて、照射範囲（視野）を放射線検出器１６全面に広げることも可能である。
　または、放射線検出器１６が十分に大きい場合は、周期パターンが形成されない検出器領域を用いて関心領域の拡大撮影を行うようにしてもよい。放射線検出器１６を複数用いてもよい。
　例えば、コリメーター・付加フィルター１１２を調整するか、又は放射線源１１に角度をつけて、図１１に示すように格子（第１格子１４及び第２格子１５）が視野内に入らないようにＸ線の照射範囲を調整するとともに移動・回転機構１３ａにより被写体Ｈを照射領域内に移動させ、放射線検出器１６において周期パターンが発生しない状態で関心領域の拡大撮影を行って拡大吸収コントラスト画像を生成することとしてもよい。
　または、放射線源１１が複数の焦点径の異なる放射線源（例えば、大焦点、小焦点）を有している場合は、図１２に示すように、予め、大焦点の放射線照射領域に格子を配置し、小焦点の放射線照射領域に格子が配置されないように構成しておき、拡大撮影時には、被写体Ｈを小焦点の照射領域の小焦点近傍に移動させて小焦点からＸ線を照射して、放射線検出器１６において周期パターンが発生しない状態で関心領域の拡大撮影を行って拡大吸収コントラスト画像を生成することとしてもよい。
　周期パターン撮影時には、格子位置の調整精度が悪いと適正なモアレ縞画像が得られないため、拡大撮影時に格子を移動させるよりも、周期パターンが形成されない検出器領域を用いて撮影を行うようにすることが好ましい。
　縞走査法を用いずに、１回の拡大撮影で拡大吸収コントラスト画像を生成することにより、撮影が簡易となるだけでなく、格子での不要な吸収がなくなるため画質が向上でき、好ましい。 For example, as shown in FIGS. 10A to 10C, at least one of the grids is retracted out of the field of view (in the x direction or the y direction), and an enlarged image of the region of interest is performed in a state where a periodic pattern does not occur to enlarge the image. Generates an absorption contrast image. As shown in FIG. 10C, it is also possible to retract both the first grid 14 and the second grid 15 to expand the irradiation range (field of view) over the entire surface of the radiation detector 16.
Alternatively, when the radiation detector 16 is sufficiently large, a magnified image of the region of interest may be performed using a detector region in which a periodic pattern is not formed. A plurality of radiation detectors 16 may be used.
For example, the collimator / additional filter 112 is adjusted, or the radiation source 11 is angled so that the lattices (first lattice 14 and second lattice 15) are not in the field of view as shown in FIG. The irradiation range of the line is adjusted, the subject H is moved into the irradiation area by the moving / rotating mechanism 13a, and the radiation detector 16 performs magnified imaging of the area of interest in a state where no periodic pattern is generated to generate a magnified absorption contrast image. You may do it.
Alternatively, when the radiation source 11 has a plurality of radiation sources having different focal diameters (for example, large focus and small focus), a lattice is arranged in advance in the irradiation region of the large focus as shown in FIG. However, the grid is not arranged in the irradiation area of the small focus, and at the time of magnified shooting, the subject H is moved to the vicinity of the small focus of the irradiation area of the small focus to irradiate X-rays from the small focus. The radiation detector 16 may perform magnified imaging of the region of interest in a state where the periodic pattern does not occur to generate a magnified absorption contrast image.
When shooting a periodic pattern, if the adjustment accuracy of the grid position is poor, an appropriate moire fringe image cannot be obtained. Therefore, rather than moving the grid during magnified shooting, shoot using the detector area where the periodic pattern is not formed. It is preferable to do so.
It is preferable to generate a magnified absorption contrast image by one magnified imaging without using the fringe scanning method because not only the imaging is simplified but also the image quality can be improved because unnecessary absorption in the grid is eliminated.
　または、以下の（１）～（４）のいずれかの手法により周期パターンの鮮明度を周期パターン撮影時よりも低下させて関心領域の拡大撮影を行うことにより拡大吸収コントラスト画像を生成することとしてもよい。
（１）図１３Ａに示すように、Ｘ線照射中かつ放射線検出器１６の蓄積中に格子の一つ又は複数を格子のスリット周期方向であるｘ方向に連続移動又はステップ移動させて撮影を行う。
（２）図１３Ｂに示すように、格子の一つ又は複数を周期パターン撮影時の位置からｚ方向に移動させた状態で撮影を行う。
（３）図１３Ｃに示すように、散乱体１９を照射野内に配置して撮影を行う。
（４）図１３Ｄに示すように、格子のいずれか又は複数を周期パターン撮影時よりも放射線照射軸周りに回転させた状態で撮影を行う。
　散乱体１９は、Ｘ線散乱が強く、吸収が弱いものが好ましい。例えば、散乱体１９は移動機構によりｘ方向又はｙ方向に移動可能に構成されていることとし、拡大撮影時に制御部５１が移動機構を制御して散乱体１９が視野内に挿入されるようにして撮影を行うこととしてもよい。 Alternatively, a magnified absorption contrast image is generated by performing magnified shooting of the region of interest by lowering the sharpness of the periodic pattern from that at the time of periodic pattern shooting by any of the following methods (1) to (4). May be good.
(1) As shown in FIG. 13A, during X-ray irradiation and accumulation of the radiation detector 16, one or more of the grids are continuously moved or stepped in the x direction, which is the slit periodic direction of the grids, to perform imaging. ..
(2) As shown in FIG. 13B, shooting is performed in a state where one or more of the grids are moved in the z direction from the position at the time of periodic pattern shooting.
(3) As shown in FIG. 13C, the scatterer 19 is arranged in the irradiation field for photographing.
(4) As shown in FIG. 13D, imaging is performed in a state where one or more of the grids are rotated around the irradiation axis as compared with the time of periodic pattern imaging.
The scatterer 19 preferably has strong X-ray scattering and weak absorption. For example, the scatterer 19 is configured to be movable in the x-direction or the y-direction by a moving mechanism, and the control unit 51 controls the moving mechanism during magnified imaging so that the scatterer 19 is inserted into the field of view. You may take a picture.
　なお、周期パターン撮影用の位置から拡大撮影用の位置に放射線源１１（コリメーター・付加フィルター１１２）、被写体台１３、第１格子１４、第２格子１５、放射線検出器１６のいずれか一つ以上を移動させる際には、センサー、監視カメラ、又はタルボ撮影により得られた画像を用いた被写体Ｈの大きさ推定等により、これらが互いにぶつからないように（干渉しないように）制御することが好ましい。 One of the radiation source 11 (collimator / additional filter 112), the subject stand 13, the first grid 14, the second grid 15, and the radiation detector 16 from the position for periodic pattern shooting to the position for magnified shooting. When moving the above, it is possible to control the subject H so that it does not collide with each other (do not interfere with each other) by estimating the size of the subject H using a sensor, a surveillance camera, or an image obtained by Talbot photography. preferable.
　次いで、制御部５１は、拡大撮影により得られた拡大吸収コントラスト画像を表示部５３に表示させる（ステップＳ６）。
　例えば、拡大吸収コントラスト画像をそのまま表示部５３に表示させる。複数の拡大吸収コントラスト画像が生成された場合は、並べて又は操作部５２の操作に応じて切り替え表示させる。または、自動再生してもよい。
　または、ステップＳ２で生成された位相コントラスト画像、散乱コントラスト画像、又は合成画像上に、拡大吸収コントラスト画像を合成して表示してもよい。 Next, the control unit 51 causes the display unit 53 to display the magnified absorption contrast image obtained by the magnified shooting (step S6).
For example, the enlarged absorption contrast image is displayed on the display unit 53 as it is. When a plurality of magnified absorption contrast images are generated, they are displayed side by side or switched according to the operation of the operation unit 52. Alternatively, it may be automatically played.
Alternatively, the enlarged absorption contrast image may be combined and displayed on the phase contrast image, the scattered contrast image, or the composite image generated in step S2.
　なお、機構精度が不十分である場合は、ステップＳ２で生成された画像上に拡大吸収コントラスト画像を合成する際には、ステップＳ１で撮影されたモアレ縞画像に基づいて吸収コントラスト画像を生成し、その吸収コントラスト画像と拡大吸収コントラスト画像で位置合わせを行って合成を行うことが好ましい。
　また、ステップＳ１で撮影されたモアレ縞画像に基づいて吸収コントラスト画像を生成し、その吸収コントラスト画像と拡大吸収コントラスト画像に基づいて、拡大撮影位置のずれ量を求め、ずれ量に基づいて拡大撮影位置を補正して拡大撮影の再撮影を行うこととしてもよい。または、撮影位置の補正量として記憶部５５に記憶しておき、次回以降の撮影時に補正量に基づいて撮影位置を補正してもよい。
　なお、拡大吸収コントラスト画像の表示は、全ての関心領域の撮影が終了した後に行ってもよい。 If the mechanism accuracy is insufficient, when the enlarged absorption contrast image is combined with the image generated in step S2, the absorption contrast image is generated based on the moire fringe image taken in step S1. It is preferable that the absorption contrast image and the enlarged absorption contrast image are aligned and combined.
Further, an absorption contrast image is generated based on the moire fringe image taken in step S1, the amount of deviation of the enlarged shooting position is obtained based on the absorption contrast image and the enlarged absorption contrast image, and the enlarged image is taken based on the amount of deviation. The position may be corrected and the magnified shooting may be retaken. Alternatively, the shooting position may be stored in the storage unit 55 as a correction amount of the shooting position, and the shooting position may be corrected based on the correction amount at the next shooting.
The enlarged absorption contrast image may be displayed after all the areas of interest have been photographed.
　次いで、制御部５１は、全ての関心領域の撮影が終了したか否かを判断する（ステップＳ７）。
　全ての関心領域の撮影が終了していないと判断した場合（ステップＳ７；ＮＯ）、制御部５１は、ステップＳ５に戻る。
　全ての関心領域の撮影が終了したと判断した場合（ステップＳ７；ＹＥＳ）、制御部５１は、ステップＳ２で生成した画像と、その画像における関心領域の位置情報と、その関心領域を拡大した拡大吸収コントラスト画像とを対応付けて記憶部５５に記憶させ（ステップＳ８）、拡大撮影制御処理を終了する。 Next, the control unit 51 determines whether or not the photographing of all the regions of interest is completed (step S7).
When it is determined that the photographing of all the regions of interest has not been completed (step S7; NO), the control unit 51 returns to step S5.
When it is determined that the shooting of all the regions of interest is completed (step S7; YES), the control unit 51 expands and enlarges the image generated in step S2, the position information of the regions of interest in the images, and the regions of interest. The absorption contrast image is associated with the image and stored in the storage unit 55 (step S8), and the magnified imaging control process is completed.
　以上説明したように、放射線撮影システム１００Ａによれば、放射線撮影装置１Ａにより第１格子１４及び第２格子１５を用いて被写体の周期パターン画像を撮影し、周期パターン画像に基づき、位相コントラスト画像、散乱コントラスト画像、これらの画像と前記周期パターン画像に基づいて生成された吸収コントラスト画像のうち二以上の画像の合成画像、のうち少なくとも一つを生成し、生成した画像に基づいて被写体に一又は複数の関心領域を設定する。そして、設定された関心領域を放射線撮影装置１Ａにより拡大撮影して関心領域が拡大された拡大吸収コントラスト画像を生成する。
　したがって、被写体に含まれるミクロンオーダーの微小構造体やクラック、ボイド等の位置を容易に特定し、その位置を拡大した拡大吸収コントラスト画像を得ることができるので、被写体に含まれるミクロンオーダーの微小構造体やクラック、ボイド等の形状や大きさを効率的に把握したり測定したりすることが可能となる。 As described above, according to the radiography system 100A, the radiography apparatus 1A captures a periodic pattern image of a subject using the first grid 14 and the second grid 15, and based on the periodic pattern image, a phase contrast image, At least one of a scattered contrast image and a composite image of two or more of these images and an absorption contrast image generated based on the periodic pattern image is generated, and one or one of the subjects is generated based on the generated image. Set multiple areas of interest. Then, the set area of interest is magnified and photographed by the radiography apparatus 1A to generate an enlarged absorption contrast image in which the area of interest is enlarged.
Therefore, the positions of micron-order microstructures, cracks, voids, etc. contained in the subject can be easily identified, and an enlarged absorption contrast image obtained by enlarging the positions can be obtained. Therefore, the micron-order microstructures contained in the subject can be obtained. It is possible to efficiently grasp and measure the shape and size of a body, a crack, a void, and the like.
　例えば、ユーザー操作により位相コントラスト画像、散乱コントラスト画像、合成画像の少なくとも一つから指定された一又は複数の領域を関心領域に設定することで、ユーザーが観察したい位置を拡大して観察することが可能となる。 For example, by setting one or more areas designated from at least one of a phase contrast image, a scattered contrast image, and a composite image as an area of interest by a user operation, the position desired by the user can be enlarged and observed. It will be possible.
　また、位相コントラスト画像、散乱コントラスト画像、合成画像の少なくとも一つを解析することにより自動的に関心領域を設定することで、被写体内部の観察を効率的に行うことが可能となる。 In addition, by automatically setting the region of interest by analyzing at least one of the phase contrast image, the scattered contrast image, and the composite image, it is possible to efficiently observe the inside of the subject.
　また、被写体の位相コントラスト画像、散乱コントラスト画像及び／又は合成画像と、その画像における関心領域の位置情報と、その関心領域を拡大した拡大吸収コントラスト画像と、を対応付けて記憶部５５に記憶しておくことで、撮影された拡大吸収コントラスト画像が被写体のどの部分のものかを容易に特定することが可能となる。 Further, the phase contrast image, the scattered contrast image and / or the composite image of the subject, the position information of the region of interest in the image, and the enlarged absorption contrast image in which the region of interest is enlarged are stored in the storage unit 55 in association with each other. By setting the image, it becomes possible to easily identify which part of the subject the captured magnified absorption contrast image belongs to.
　なお、上述した本実施形態における記述は、本発明に係る好適な一例であり、これに限定されるものではない。 Note that the description in the present embodiment described above is a preferable example according to the present invention, and is not limited thereto.
　例えば、上記実施形態では、縞走査法による撮影時に第２格子１５を第１格子１４に対して移動させる方式のタルボ干渉計を用いた放射線撮影装置を例にとり説明したが、第１格子１４を第２格子１５に対して移動させる構成としてもよい。
　また、上記実施形態では、縞走査法により撮影を行って複数の周期パターン画像を取得して位相コントラスト画像、散乱コントラスト画像、吸収コントラスト画像を生成する場合を例にとり説明したが、撮影により１枚の周期パターン画像を取得して、１枚の周期パターン画像からフーリエ変換法により位相コントラスト画像、散乱コントラスト画像、吸収コントラスト画像を生成することとしてもよい。また、走査方式（例えば、参照文献４（Masashi Kageyama et al., X-ray phase-imaging scanner with tiled bent gratings for large-field-of-view nondestructive testing, NDT and E International, 105, 19-24, 2019）に記載のように、装置に対して被写体Ｈを移動させる、もしくは被写体Ｈに対して装置を移動させて撮影。）で位相コントラスト画像、散乱コントラスト画像、吸収コントラスト画像を生成することとしてもよい。その場合、拡大撮影も同様に走査方式としても良い。 For example, in the above embodiment, a radiography apparatus using a Talbot interferometer in which the second grid 15 is moved with respect to the first grid 14 during imaging by the fringe scanning method has been described as an example, but the first grid 14 is used as an example. It may be configured to move with respect to the second lattice 15.
Further, in the above embodiment, the case where a plurality of periodic pattern images are acquired by the fringe scanning method to generate a phase contrast image, a scattered contrast image, and an absorption contrast image has been described as an example, but one image is taken by photographing. The periodic pattern image of the above may be acquired, and a phase contrast image, a scattered contrast image, and an absorption contrast image may be generated from one periodic pattern image by the Fourier conversion method. In addition, a scanning method (for example, Reference 4 (Masashi Kageyama et al., X-ray phase-imaging scanner with tiled bent gratings for large-field-of-view nondestructive testing, NDT and E International, 105, 19-24, As described in 2019), the phase contrast image, the scattered contrast image, and the absorption contrast image may be generated by moving the subject H with respect to the device or moving the device with respect to the subject H for shooting.) Good. In that case, the magnified shooting may be similarly performed by the scanning method.
　また、放射線検出器１６の画素が、一般的な放射線検出器の画素サイズよりもはるかに小さい小画素により構成されている場合は、第１格子１４により生成される自己像を放射線検出器１６で捉えることができるため、第２格子１５を有さない構成としてもよい。
　また、周期パターン撮影時にタルボ次数を変更し、第１格子１４と放射線検出器１６の距離を離して自己像を拡大すれば、一般的な画素サイズの放射線検出器１６であっても自己像を捉えることができるため、第２格子１５を有さない構成としてもよい。 Further, when the pixels of the radiation detector 16 are composed of small pixels much smaller than the pixel size of a general radiation detector, the radiation detector 16 produces a self-image generated by the first grid 14. Since it can be captured, it may be configured without the second grid 15.
Further, if the Talbot order is changed at the time of periodic pattern photographing and the self-image is enlarged by separating the first grid 14 and the radiation detector 16, the self-image can be obtained even with a general pixel size radiation detector 16. Since it can be captured, the configuration may not have the second grid 15.
　また、上記実施形態においては、タルボ干渉計を例にとり説明したが、放射線源１１の近傍に、線源格子１２を備えるタルボ・ロー干渉計においても本発明を適用することが可能である。例えば、図１４に示すように、複数の放射線源１１を用いる構成や、焦点切替機能を持つ放射線源１１を用いる場合は、周期パターン撮影時は線源格子１２を用いたタルボ・ロー干渉計が好ましい。なお、タルボ・ロー干渉計の場合、線源格子１２を移動させる移動機構を備え、縞走査法による撮影を行う場合は第１格子１４及び第２格子１５に対して線源格子１２を移動させることとしてもよい。また、拡大撮影において格子を視野外に退避させる構成の場合は線源格子１２も視野外に移動させる。 Further, in the above embodiment, the Talbot interferometer has been described as an example, but the present invention can also be applied to a Talbot low interferometer provided with a radiation source grid 12 in the vicinity of the radiation source 11. For example, as shown in FIG. 14, when a configuration using a plurality of radiation sources 11 or a radiation source 11 having a focus switching function is used, a Talbot low interferometer using a radiation source grid 12 is used during periodic pattern imaging. preferable. In the case of the Talbot low interferometer, a moving mechanism for moving the source grid 12 is provided, and when photographing by the fringe scanning method, the source grid 12 is moved with respect to the first grid 14 and the second grid 15. It may be that. Further, in the case of a configuration in which the grid is retracted out of the field of view in magnified photography, the radiation source grid 12 is also moved out of the field of view.
　また、放射線源、コリメーター・付加フィルター、被写体台、格子、放射線検出器の移動機構や移動・回転機構は、図１に図示した全てを備える必要はなく、その放射線撮影システムで撮影に必要なもののみ備えていればよい。 Further, the radiation source, the collimator / additional filter, the subject stand, the grid, the moving mechanism and the moving / rotating mechanism of the radiation detector do not need to be provided with all of those shown in FIG. 1, and are necessary for photographing by the radiography system. You only need to have things.
　また、上記実施形態においては、コントローラー５の制御部５１が放射線撮影装置１Ａの各部に直接接続されている構成としたが、放射線撮影装置１Ａに各部を制御する制御部を備え、この放射線撮影装置１Ａ側の制御部と通信部を介して制御部５１が放射線撮影装置１Ａの各部を制御する構成としてもよい。 Further, in the above embodiment, the control unit 51 of the controller 5 is directly connected to each part of the radiography imaging device 1A, but the radiography apparatus 1A is provided with a control unit for controlling each part, and this radiography apparatus The control unit 51 may control each unit of the radiography apparatus 1A via the control unit and the communication unit on the 1A side.
　また、例えば、上記の説明では、本発明に係るプログラムのコンピューター読み取り可能な媒体としてハードディスクや半導体の不揮発性メモリー等を使用した例を開示したが、この例に限定されない。その他のコンピューター読み取り可能な媒体として、ＣＤ-ＲＯＭ等の可搬型記録媒体を適用することが可能である。また、本発明に係るプログラムのデータを通信回線を介して提供する媒体として、キャリアウエーブ(搬送波)も適用される。 Further, for example, in the above description, an example in which a hard disk, a non-volatile memory of a semiconductor, or the like is used as a computer-readable medium for the program according to the present invention has been disclosed, but the present invention is not limited to this example. As another computer-readable medium, a portable recording medium such as a CD-ROM can be applied. A carrier wave is also applied as a medium for providing data of a program according to the present invention via a communication line.
　その他、放射線撮影システムを構成する各装置の細部構成及び細部動作に関しても、発明の趣旨を逸脱することのない範囲で適宜変更可能である。 In addition, the detailed configuration and detailed operation of each device constituting the radiography system can be appropriately changed as long as the purpose of the invention is not deviated.
　本発明は、材料や製品の検査において利用することができる。 The present invention can be used in the inspection of materials and products.
１００Ａ　放射線撮影システム
１Ａ　放射線撮影装置
１１　放射線源
１３　被写体台
１４　第１格子
１５　第２格子
１６　放射線検出器
１７　支柱
１１１　焦点
１１２　コリメーター・付加フィルター
１９　散乱体
５　コントローラー
５１　制御部
５２　操作部
５３　表示部
５４　通信部
５５　記憶部 100A Radiation imaging system 1A Radiation imaging device 11 Radiation source 13 Subject stand 14 First grid 15 Second grid 16 Radiation detector 17 Support 111 Focus 112 Collimator / additional filter 19 Scatterer 5 Controller 51 Control unit 52 Operation unit 53 Display unit 54 Communication unit 55 Storage unit

Claims (15)

  1. 　放射線源と、１又は複数の格子と、放射線検出器と、が放射線照射軸方向に並んで設けられた放射線撮影装置を備える放射線撮影システムであって、
    　前記放射線撮影装置により前記格子を用いて被写体の周期パターン画像を撮影し、前記周期パターン画像に基づき、位相コントラスト画像、散乱コントラスト画像、これらの画像と前記周期パターン画像に基づいて生成された吸収コントラスト画像のうち二以上の画像の合成画像、のうち少なくとも一つを生成する画像生成手段と、
    　前記画像生成手段により生成された画像に基づいて前記被写体に一又は複数の関心領域を設定する関心領域設定手段と、
    　前記関心領域設定手段により設定された関心領域を前記放射線撮影装置により拡大撮影して前記関心領域が拡大された拡大吸収コントラスト画像を生成する拡大吸収コントラスト画像生成手段と、
    　を備える放射線撮影システム。     A radiation imaging system including a radiation imaging device in which a radiation source, one or more grids, and a radiation detector are provided side by side in the irradiation axis direction.
    A periodic pattern image of a subject is photographed by the radiation photographing apparatus using the lattice, a phase contrast image, a scattered contrast image, and an absorption contrast generated based on these images and the periodic pattern image based on the periodic pattern image. An image generation means for generating at least one of two or more composite images of an image,
    An area of interest setting means for setting one or a plurality of areas of interest for the subject based on an image generated by the image generation means.
    An enlarged absorption contrast image generation means for generating an enlarged absorption contrast image in which the area of interest is enlarged by taking an enlarged image of the area of interest set by the area of interest setting means by the radiography apparatus.
    Radiation imaging system equipped with.
  2. 　前記位相コントラスト画像は、微分位相画像、位相ＣＴ画像、又は位相画像である請求項１に記載の放射線撮影システム。 The radiography system according to claim 1, wherein the phase contrast image is a differential phase image, a phase CT image, or a phase image.
  3. 　前記散乱コントラスト画像は、小角散乱画像、小角散乱ＣＴ画像、又は小角散乱配向画像である請求項１又は２に記載の放射線撮影システム。 The radiography system according to claim 1 or 2, wherein the scattering contrast image is a small-angle scattering image, a small-angle scattering CT image, or a small-angle scattering orientation image.
  4. 　前記合成画像は、前記位相コントラスト画像、前記散乱コントラスト画像、前記吸収コントラスト画像のうち二つ以上の画像全体又は画像の一部を重みづけして加算、減算、除算、もしくは乗算して重ね合わせた画像、又は色を用いて重ね合わせ処理した画像である請求項１～３のいずれか一項に記載の放射線撮影システム。 In the composite image, two or more of the phase contrast image, the scattered contrast image, and the absorption contrast image, or a part of the image, are weighted and added, subtracted, divided, or multiplied and superimposed. The radiography system according to any one of claims 1 to 3, which is an image or an image superposed using colors.
  5. 　前記吸収コントラスト画像は、吸収画像、微分吸収画像、又は吸収ＣＴ画像であり、前記拡大吸収コントラスト画像は、前記吸収コントラスト画像よりも前記被写体を拡大して撮影された吸収画像、微分吸収画像、又は吸収ＣＴ画像である請求項１～４のいずれか一項に記載の放射線撮影システム。 The absorption contrast image is an absorption image, a differential absorption image, or an absorption CT image, and the enlarged absorption contrast image is an absorption image, a differential absorption image, or a differential absorption image taken by enlarging the subject more than the absorption contrast image. The radiography system according to any one of claims 1 to 4, which is an absorption CT image.
  6. 　前記拡大吸収コントラスト画像生成手段は、縞走査法またはフーリエ変換法を用いて、前記周期パターン画像から前記拡大吸収コントラスト画像を生成する請求項１～５のいずれか一項に記載の放射線撮影システム。 The radiography system according to any one of claims 1 to 5, wherein the magnifying absorption contrast image generation means generates the magnifying absorption contrast image from the periodic pattern image by using a fringe scanning method or a Fourier transform method.
  7. 　前記拡大吸収コントラスト画像生成手段は、前記放射線撮影装置により、前記１又は複数の格子を、前記格子のスリット周期方向に移動させながら前記関心領域の拡大撮影を行うか、前記周期パターン画像の撮影時の位置に対して前記放射線照射軸方向に移動させた状態で前記関心領域の拡大撮影を行うか、もしくは前記周期パターン画像の撮影時に対して放射線照射軸周りに回転させた状態で前記関心領域の拡大撮影を行うか、又は、散乱体を視野内に配置して前記関心領域の拡大撮影を行って、前記拡大吸収コントラスト画像を生成する請求項１～５のいずれか一項に記載の放射線撮影システム。 The magnifying absorption contrast image generating means performs magnified imaging of the region of interest while moving the one or a plurality of lattices in the slit periodic direction of the lattice by the radiographing apparatus, or at the time of photographing the periodic pattern image. The magnified image of the region of interest is taken while being moved in the direction of the irradiation axis with respect to the position of, or the region of interest is rotated around the irradiation axis with respect to the time of photographing the periodic pattern image. The radiography according to any one of claims 1 to 5, wherein a magnified image is taken or a scatterer is placed in a field of view to perform an enlarged image of the region of interest to generate the magnified absorption contrast image. system.
  8. 　前記拡大吸収コントラスト画像生成手段は、前記放射線撮影装置において、少なくとも一つの前記格子を視野外に退避させるか又は前記放射線検出器における前記格子による周期パターンが形成されない検出領域を用いて前記関心領域の拡大撮影を行って、前記拡大吸収コントラスト画像を生成する請求項１～５のいずれか一項に記載の放射線撮影システム。 In the radiography apparatus, the magnifying absorption contrast image generating means retracts at least one of the lattices out of the field of view, or uses a detection region in the radiation detector in which a periodic pattern is not formed by the lattices to generate a region of interest. The radiography system according to any one of claims 1 to 5, which performs magnified imaging to generate the magnified absorption contrast image.
  9. 　前記拡大吸収コントラスト画像生成手段は、前記放射線撮影装置において、前記放射線

    検出器と前記被写体との間の距離を長くするか、前記放射線源と前記被写体の間の距離を短くするか、又はその両方により、前記関心領域を拡大撮影する請求項１～８のいずれか一項に記載の放射線撮影システム。     The magnified absorption contrast image generation means is the radiation in the radiographing apparatus.

    Any of claims 1 to 8 for magnifying the region of interest by increasing the distance between the detector and the subject, reducing the distance between the radiation source and the subject, or both. The radiography system described in paragraph 1.
  10. 　前記放射線撮影装置は、異なる複数の焦点径での撮影が可能に構成され、
    　前記拡大吸収コントラスト画像生成手段による前記拡大撮影時は、前記画像生成手段による前記周期パターン画像の撮影時よりも小さい焦点を用いる請求項１～９のいずれか一項に記載の放射線撮影システム。     The radiography apparatus is configured to be capable of photographing at a plurality of different focal diameters.
    The radiographic imaging system according to any one of claims 1 to 9, wherein a focus smaller than that at the time of photographing the periodic pattern image by the image generating means is used at the time of the magnified imaging by the magnifying absorption contrast image generating means.
  11. 　前記関心領域設定手段は、前記被写体における、ユーザー操作により前記位相コントラスト画像、前記散乱コントラスト画像、前記合成画像の少なくとも一つから指定された一又は複数の領域を前記関心領域に設定する請求項１～１０のいずれか一項に記載の放射線撮影システム。 The area of interest setting means sets one or a plurality of areas designated from at least one of the phase contrast image, the scattered contrast image, and the composite image in the subject by user operation. The radiography system according to any one of 10 to 10.
  12. 　前記関心領域設定手段は、前記位相コントラスト画像、前記散乱コントラスト画像、前記合成画像の少なくとも一つを解析することにより前記一又は複数の関心領域を設定する請求項１～１０のいずれか一項に記載の放射線撮影システム。 The area of interest setting means according to any one of claims 1 to 10, wherein the area of interest is set by analyzing at least one of the phase contrast image, the scattered contrast image, and the composite image. The radiography system described.
  13. 　前記画像生成手段により生成された画像と、当該画像における前記関心領域の位置情報と、その関心領域を拡大した拡大吸収コントラスト画像と、を対応付けて記憶する記憶手段を備える請求項１～１２のいずれか一項に記載の放射線撮影システム。 Claims 1 to 12 include a storage means for storing an image generated by the image generation means, position information of the region of interest in the image, and an enlarged absorption contrast image in which the region of interest is enlarged. The radiography system according to any one item.
  14. 　一又は複数の拡大率又は空間分解能を設定する設定手段を備え、
    　前記拡大吸収コントラスト画像生成手段は、前記関心領域ごとに、前記設定手段により設定された拡大率又は空間分解能で決まる視野サイズに応じて前記関心領域を分割し複数回撮影する、または前記関心領域内の一点を中心に拡大率を変化させて複数回撮影する請求項１～１３のいずれか一項に記載の放射線撮影システム。     A setting means for setting one or more magnifications or spatial resolutions is provided.
    The magnifying and absorbing contrast image generation means divides the region of interest for each region of interest according to the field of view size determined by the magnification or spatial resolution set by the setting means and photographs the region of interest a plurality of times, or within the region of interest. The radiography system according to any one of claims 1 to 13, wherein the magnification is changed around one point and a plurality of times of imaging are performed.
  15. 　放射線源と、１又は複数の格子と、放射線検出器と、が放射線照射軸方向に並んで設けられた放射線撮影装置を備える拡大吸収コントラスト画像生成方法であって、
    　前記放射線撮影装置により前記格子を用いて被写体の周期パターン画像を撮影し、前記周期パターン画像に基づき、位相コントラスト画像、散乱コントラスト画像、これらの画像と前記周期パターン画像に基づいて生成された吸収コントラスト画像のうち二以上の画像の合成画像、のうち少なくとも一つを生成する画像生成工程と、
    　前記画像生成工程において生成された画像に基づいて前記被写体に一又は複数の関心領域を設定する関心領域設定工程と、
    　前記関心領域設定工程において設定された関心領域を前記放射線撮影装置により拡大撮影して前記関心領域が拡大された拡大吸収コントラスト画像を生成する拡大吸収画像生成工程と、
    　を含む拡大吸収コントラスト画像生成方法。     A magnifying absorption contrast image generation method comprising a radiographing apparatus in which a radiation source, one or more grids, and a radiation detector are provided side by side in the irradiation axis direction.
    A periodic pattern image of a subject is photographed by the radiation photographing apparatus using the lattice, a phase contrast image, a scattered contrast image, and an absorption contrast generated based on these images and the periodic pattern image based on the periodic pattern image. An image generation step of generating at least one of two or more composite images of an image,
    An area of interest setting step of setting one or a plurality of areas of interest to the subject based on the image generated in the image generation step.
    An enlarged absorption image generation step of generating an enlarged absorption contrast image in which the area of interest is enlarged by taking an enlarged image of the area of interest set in the area of interest setting step by the radiography apparatus.
    Enlarged absorption contrast image generation method including.
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